I have a low-end Harbor Freight 8 gallon air compressor that has many
times over earned its $100 cost.

However, there are times when I would like to have a larger air supply
tank such as when I am blowing out my irrigation system. Of course the
steady-state is limited by the compressor motor to about 4-5 CFM@90 psi.

But I was wondering whether I could extend at least the initial volume
by adding an additional tank.

Harbor Freight for example sells an 11 gallon portable air tank
(http://www.harborfreight.com/11-gall...ank-65595.html)
for about $38. It is rated up to 125 psi (same as my compressor) and
comes with a gauge and a tire-type fitting.

I was thinking that I could re-plumb to NPT and attach it to the drain
hole on my compressor tank (with a T-fitting and ball valve to still
allow drainage).

This would then give me effectively 19 gallons of initial air supply.

Of course, I would need to be careful about duty cycle since filling up
19 gallons vs. 8 gallons would be like doing 2 1/2 continuous fills of
my original tank.

But assuming that I am careful about duty cycle is this a reasonable way
to temporarily extend the initial air supply for occassional uses where
I need to get the advantages of a larger tank?

(Note that it seems that several of the Harbor Freight compressors use
the same HP motor with similar CFM ratings for a range of tank sizes --
probably because the HP is ultimately limited by the 110V 15A supply
circuit)

Thanks!

Don't know if that is possible. I don't know who makes that Harbor
Freight that you have, but if they have a U.S. number, I would call them
and talk to them about doing that. Or talk to someone local that knows
air compressor's and could guide you on that.

Paul T.


On Sun, 23 Oct 2011 20:48:18 -0400, blueman wrote:

I have a low-end Harbor Freight 8 gallon air compressor that has many
times over earned its $100 cost.

However, there are times when I would like to have a larger air supply
tank such as when I am blowing out my irrigation system. Of course the
steady-state is limited by the compressor motor to about 4-5 CFM@90 psi.

But I was wondering whether I could extend at least the initial volume
by adding an additional tank.

Harbor Freight for example sells an 11 gallon portable air tank
(http://www.harborfreight.com/11-gall...ank-65595.html)
for about $38. It is rated up to 125 psi (same as my compressor) and
comes with a gauge and a tire-type fitting.

I was thinking that I could re-plumb to NPT and attach it to the drain
hole on my compressor tank (with a T-fitting and ball valve to still
allow drainage).

This would then give me effectively 19 gallons of initial air supply.

Of course, I would need to be careful about duty cycle since filling up
19 gallons vs. 8 gallons would be like doing 2 1/2 continuous fills of
my original tank.

But assuming that I am careful about duty cycle is this a reasonable way
to temporarily extend the initial air supply for occassional uses where
I need to get the advantages of a larger tank?

(Note that it seems that several of the Harbor Freight compressors use
the same HP motor with similar CFM ratings for a range of tank sizes --
probably because the HP is ultimately limited by the 110V 15A supply
circuit)

Thanks!

On 10/23/2011 7:48 PM, blueman wrote:

However, there are times when I would like to have a larger air supply
tank such as when I am blowing out my irrigation system. Of course the
steady-state is limited by the compressor motor to about 4-5 CFM@90 psi.

Had an add-on tank for a long time but recently gave it away when I
moved to a smaller shop. I never found it to be much of a practical
advantage, all things considered.

Hardly noticeable, AAMOF.

YMMV ...

--
www.eWoodShop.com
Last update: 4/15/2010
KarlCaillouet@ (the obvious)
http://gplus.to/eWoodShop

"blueman" wrote in message
...
I have a low-end Harbor Freight 8 gallon air compressor that has many
times over earned its $100 cost.

However, there are times when I would like to have a larger air supply
tank such as when I am blowing out my irrigation system. Of course the
steady-state is limited by the compressor motor to about 4-5 CFM@90 psi.

But I was wondering whether I could extend at least the initial volume
by adding an additional tank.

Harbor Freight for example sells an 11 gallon portable air tank
(http://www.harborfreight.com/11-gall...ank-65595.html)
for about $38. It is rated up to 125 psi (same as my compressor) and
comes with a gauge and a tire-type fitting.

I was thinking that I could re-plumb to NPT and attach it to the drain
hole on my compressor tank (with a T-fitting and ball valve to still
allow drainage).

This would then give me effectively 19 gallons of initial air supply.

Of course, I would need to be careful about duty cycle since filling up
19 gallons vs. 8 gallons would be like doing 2 1/2 continuous fills of
my original tank.

But assuming that I am careful about duty cycle is this a reasonable way
to temporarily extend the initial air supply for occassional uses where
I need to get the advantages of a larger tank?

(Note that it seems that several of the Harbor Freight compressors use
the same HP motor with similar CFM ratings for a range of tank sizes --
probably because the HP is ultimately limited by the 110V 15A supply
circuit)

Thanks!

Your logic and reasoning are just fine. Go ahead and add an
external tank, it shouldn't harm your existing unit.
Art

On Sun, 23 Oct 2011 20:48:18 -0400, blueman wrote:

I have a low-end Harbor Freight 8 gallon air compressor that has many
times over earned its $100 cost.

However, there are times when I would like to have a larger air supply
tank such as when I am blowing out my irrigation system. Of course the
steady-state is limited by the compressor motor to about 4-5 CFM@90 psi.

But I was wondering whether I could extend at least the initial volume
by adding an additional tank.


There are numerous ways to pipe the tank in line. Your reasoning is
correct, you get the initial burst, but that is all.

I'd pipe it in, but I'd put a valve in the line to shut it off. Two
reasons for that. There is no good reason to fill that tank if you
are not going to need the backup of air. Saves both time and energy
at startup for normal work.

Second, you can fill it, close the valve, and have it ready for use.
You can also open the valve and use that air if you only need a little
shot of it and not have to start the compressor.

P.H. T. wrote:
Don't know if that is possible. I don't know who makes that Harbor
Freight that you have, but if they have a U.S. number, I would call
them and talk to them about doing that. Or talk to someone local that
knows air compressor's and could guide you on that.

Paul T.



Yes - it is very possible. Why would anyone respond with "I don't know if
that is possible"? Hell - better to watch the responses and see. Possible
is one thing - probable is quite another.

--

-Mike-

Artemus wrote:


Your logic and reasoning are just fine. Go ahead and add an
external tank, it shouldn't harm your existing unit.
Art

Will not harm it, but will it help him - which is what he asked? For me - I
do not know. I understand about cascadde units that do this kind of thing,
but I don't understand the demand requirements of those cascades. So far -
not a single reply has offered any real knowledge to the OP's question...

--

-Mike-

On 10/23/2011 7:48 PM, blueman wrote:
I have a low-end Harbor Freight 8 gallon air compressor that has many
times over earned its $100 cost.

However, there are times when I would like to have a larger air supply
tank such as when I am blowing out my irrigation system. Of course the
steady-state is limited by the compressor motor to about 4-5 CFM@90 psi.

But I was wondering whether I could extend at least the initial volume
by adding an additional tank.

Harbor Freight for example sells an 11 gallon portable air tank
(http://www.harborfreight.com/11-gall...ank-65595.html)
for about $38. It is rated up to 125 psi (same as my compressor) and
comes with a gauge and a tire-type fitting.

I was thinking that I could re-plumb to NPT and attach it to the drain
hole on my compressor tank (with a T-fitting and ball valve to still
allow drainage).

This would then give me effectively 19 gallons of initial air supply.

Of course, I would need to be careful about duty cycle since filling up
19 gallons vs. 8 gallons would be like doing 2 1/2 continuous fills of
my original tank.

But assuming that I am careful about duty cycle is this a reasonable way
to temporarily extend the initial air supply for occassional uses where
I need to get the advantages of a larger tank?

(Note that it seems that several of the Harbor Freight compressors use
the same HP motor with similar CFM ratings for a range of tank sizes --
probably because the HP is ultimately limited by the 110V 15A supply
circuit)

Thanks!

If you are talking about blowing out a sprinkler system I doubt the
capacity you are gaining will help. Long ago I had a 80 gallon tank
with a small pump, I could empty it in about 15 seconds when blowing a
lot of air. My nephew used to be in the sprinkler business and rented a
commercial compressor for blowing out the systems.

blueman wrote in
:

I have a low-end Harbor Freight 8 gallon air compressor that has many
times over earned its $100 cost.

However, there are times when I would like to have a larger air supply
tank such as when I am blowing out my irrigation system. Of course the
steady-state is limited by the compressor motor to about 4-5 CFM@90
psi.


*snip*

But assuming that I am careful about duty cycle is this a reasonable
way to temporarily extend the initial air supply for occassional uses
where I need to get the advantages of a larger tank?


*snip*


Thanks!


Where it might make a difference is in air hungry intermittent duty
tools like air wrenches. The extra reserve of air would allow the tool
to run longer (perhaps enough to finish the job) before the compressor
kicks on.

If you do this, make sure to open the compressor regulator to charge the
tank fully and then put another regulator before the tool connection.
If all you charge the tank with is 30 psi, you won't see much difference
at all. Charge to 100 or 120 psi and you'll notice the difference.

Puckdropper

On Oct 23, 5:48*pm, blueman wrote:
I have a low-end Harbor Freight 8 gallon air compressor that has many
times over earned its $100 cost.

However, there are times when I would like to have a larger air supply
tank such as when I am blowing out my irrigation system. Of course the
steady-state is limited by the compressor motor to about 4-5 CFM@90 psi.

But I was wondering whether I could extend at least the initial volume
by adding an additional tank.

Harbor Freight for example *sells an 11 gallon portable air tank
(http://www.harborfreight.com/11-gall...ank-65595.html)
for about $38. It is rated up to 125 psi (same as my compressor) and
comes with a gauge and a tire-type fitting.

I was thinking that I could re-plumb to NPT and attach it to the drain
hole on my compressor tank (with a T-fitting and ball valve to still
allow drainage).

This would then give me effectively 19 gallons of initial air supply.

Of course, I would need to be careful about duty cycle since filling up
19 gallons vs. 8 gallons would be like doing 2 1/2 continuous fills of
my original tank.

But assuming that I am careful about duty cycle is this a reasonable way
to temporarily extend the initial air supply for occassional uses where
I need to get the advantages of a larger tank?

(Note that it seems that several of the Harbor Freight compressors use
the same HP motor with similar CFM ratings for a range of tank sizes --
probably because the HP is ultimately limited by the 110V 15A supply
circuit)

Thanks!

Yes, your idea will be useful in application you describe (blow out
sprinkler system)

I did some "back of the envelop" calcs.

Assuming a sprinkler zone has about 100ft of 3/4" PVC pipe & zone's
total flow is about 15 gpm.

Charge your compressed air tanks to maximum pressure
but I'd recommend using a pressure regulator in the supply hose to the
sprinkler system.....set at no higher than 50 psi.

PVC piping is not meant to be used with compressed air.. ...... there
is a danger of brittle failure.
Safety glasses & cleared area are highly recommended.

Your original compressor setup will blow out a single zone for about
25 secs ....kinda short.

Add the 11 gallon tank & bump your total storage to 19 gallons, you
can blow out a single zone for about 70 secs.
Two blown outs per zone should do the trick.

I'd plumb the tanks together with 1/2" pipe minimum and use Ed'
suggestion of a valve between the tanks.
You can use the valve to select total compressed air volume and
control duty cycle.

cheers
Bob

Usually morning muddleheadedness. Leon?
LOL

-----------

"Leon" wrote in message
...
If you are talking about blowing out a sprinkler system I doubt the
capacity you are gaining will help. Long ago I had a 80 gallon tank
with a small pump, I could empty it in about 15 seconds when blowing a
lot of air. My nephew used to be in the sprinkler business and rented a
commercial compressor for blowing out the systems.

DD_BobK wrote:


PVC piping is not meant to be used with compressed air.. ...... there
is a danger of brittle failure.
Safety glasses & cleared area are highly recommended.


This should not be an issue for him since the PVC lines are open and he's
blowing air through them - correct? It's not like he's charging those
lines.

--

-Mike-

On 10/24/2011 2:25 AM, DD_BobK wrote:
On Oct 23, 5:48 pm, wrote:
I have a low-end Harbor Freight 8 gallon air compressor that has many
times over earned its $100 cost.

However, there are times when I would like to have a larger air supply
tank such as when I am blowing out my irrigation system. Of course the
steady-state is limited by the compressor motor to about 4-5 CFM@90 psi.

But I was wondering whether I could extend at least the initial volume
by adding an additional tank.

Harbor Freight for example sells an 11 gallon portable air tank
(http://www.harborfreight.com/11-gall...ank-65595.html)
for about $38. It is rated up to 125 psi (same as my compressor) and
comes with a gauge and a tire-type fitting.

I was thinking that I could re-plumb to NPT and attach it to the drain
hole on my compressor tank (with a T-fitting and ball valve to still
allow drainage).

This would then give me effectively 19 gallons of initial air supply.

Of course, I would need to be careful about duty cycle since filling up
19 gallons vs. 8 gallons would be like doing 2 1/2 continuous fills of
my original tank.

But assuming that I am careful about duty cycle is this a reasonable way
to temporarily extend the initial air supply for occassional uses where
I need to get the advantages of a larger tank?

(Note that it seems that several of the Harbor Freight compressors use
the same HP motor with similar CFM ratings for a range of tank sizes --
probably because the HP is ultimately limited by the 110V 15A supply
circuit)

Thanks!

Yes, your idea will be useful in application you describe (blow out
sprinkler system)

I did some "back of the envelop" calcs.

Assuming a sprinkler zone has about 100ft of 3/4" PVC pipe& zone's
total flow is about 15 gpm.

Charge your compressed air tanks to maximum pressure
but I'd recommend using a pressure regulator in the supply hose to the
sprinkler system.....set at no higher than 50 psi.

PVC piping is not meant to be used with compressed air.. ...... there
is a danger of brittle failure.
Safety glasses& cleared area are highly recommended.

Your original compressor setup will blow out a single zone for about
25 secs ....kinda short.

Add the 11 gallon tank& bump your total storage to 19 gallons, you
can blow out a single zone for about 70 secs.
Two blown outs per zone should do the trick.

I'd plumb the tanks together with 1/2" pipe minimum and use Ed'
suggestion of a valve between the tanks.
You can use the valve to select total compressed air volume and
control duty cycle.

cheers
Bob

Did you calculate for the fact that pushing a liquid "up" requires a lot
of continuous air flow? And concerning your blow time, how much of that
is way below 50 psi which would be much less effective?
From some that did this for a living he would run the compressed air at
a continuous pressure for 10 -15 minutes. And calculations for 100'
might be correct but I had a small yard and probably had 250' of
underground line on one run, not to mention all the heads that are
leaking air.

Do you have to do aerobics when you hold up a glass of water?

It takes pressure, not flow.

-------
"Leon" wrote in message
...
Did you calculate for the fact that pushing a liquid "up" requires a lot
of continuous air flow? And concerning your blow time, how much of that
is way below 50 psi which would be much less effective?
From some that did this for a living he would run the compressed air at
a continuous pressure for 10 -15 minutes. And calculations for 100'
might be correct but I had a small yard and probably had 250' of
underground line on one run, not to mention all the heads that are
leaking air.

Ed Pawlowski writes:

On Sun, 23 Oct 2011 20:48:18 -0400, blueman wrote:

I have a low-end Harbor Freight 8 gallon air compressor that has many
times over earned its $100 cost.

However, there are times when I would like to have a larger air supply
tank such as when I am blowing out my irrigation system. Of course the
steady-state is limited by the compressor motor to about 4-5 CFM@90 psi.

But I was wondering whether I could extend at least the initial volume
by adding an additional tank.


There are numerous ways to pipe the tank in line. Your reasoning is
correct, you get the initial burst, but that is all.

I'd pipe it in, but I'd put a valve in the line to shut it off. Two
reasons for that. There is no good reason to fill that tank if you
are not going to need the backup of air. Saves both time and energy
at startup for normal work.

Second, you can fill it, close the valve, and have it ready for use.
You can also open the valve and use that air if you only need a little
shot of it and not have to start the compressor.

All good points -- I actually am planning on doing that for all the
reasons you mention...

Leon lcb11211@swbelldotnet writes:
If you are talking about blowing out a sprinkler system I doubt the
capacity you are gaining will help. Long ago I had a 80 gallon tank
with a small pump, I could empty it in about 15 seconds when blowing a
lot of air. My nephew used to be in the sprinkler business and rented
a commercial compressor for blowing out the systems.

Well, I have been doing it successfully for the past 7 years on a 9 zone
sprinkler system (with 1" feed pipe) and about 10 gpm per zone. We live
in the Boston area with deep cold spells and I have not had any
problems.

It takes about 3-4 full tank boluses to blow out each zone (i.e. to the
point where i just get 'steam' rather than water coming out). Just to
be sure, I run it about 6-7 times per zone.

On each tank full, I get about 30-40 seconds of good initial blow before
the pressure drops down too low to lift the heads or move the rotors.

My hope was that with 2.5x the volume of the current configuration, that
I would get a better blowout and/or require fewer repeats per zone. In
particular, I was hoping to get the initial blow to last longer, say
maybe 1 minute or so. Of course, one could say if it ain't broke don't
fix it, but I figure it can't hurt.

Puckdropper puckdropper(at)yahoo(dot)com writes:

blueman wrote in
:

I have a low-end Harbor Freight 8 gallon air compressor that has many
times over earned its $100 cost.

However, there are times when I would like to have a larger air supply
tank such as when I am blowing out my irrigation system. Of course the
steady-state is limited by the compressor motor to about 4-5 CFM@90
psi.


*snip*

But assuming that I am careful about duty cycle is this a reasonable
way to temporarily extend the initial air supply for occassional uses
where I need to get the advantages of a larger tank?


*snip*


Thanks!


Where it might make a difference is in air hungry intermittent duty
tools like air wrenches. The extra reserve of air would allow the tool
to run longer (perhaps enough to finish the job) before the compressor
kicks on.

If you do this, make sure to open the compressor regulator to charge the
tank fully and then put another regulator before the tool connection.
If all you charge the tank with is 30 psi, you won't see much difference
at all. Charge to 100 or 120 psi and you'll notice the difference.


Well, my reasoning for attaching in via the drain hole is that then I
would be connecting before the regulator and at full pressure (which
maxes out on my compressor at about 110 psi). That way both tanks would
be before the regulator...

DD_BobK writes:

On Oct 23, 5:48Â*pm, blueman wrote:
I have a low-end Harbor Freight 8 gallon air compressor that has many
times over earned its $100 cost.

However, there are times when I would like to have a larger air supply
tank such as when I am blowing out my irrigation system. Of course the
steady-state is limited by the compressor motor to about 4-5 CFM@90 psi.

But I was wondering whether I could extend at least the initial volume
by adding an additional tank.

Harbor Freight for example Â*sells an 11 gallon portable air tank
(http://www.harborfreight.com/11-gall...ank-65595.html)
for about $38. It is rated up to 125 psi (same as my compressor) and
comes with a gauge and a tire-type fitting.

I was thinking that I could re-plumb to NPT and attach it to the drain
hole on my compressor tank (with a T-fitting and ball valve to still
allow drainage).

This would then give me effectively 19 gallons of initial air supply.

Of course, I would need to be careful about duty cycle since filling up
19 gallons vs. 8 gallons would be like doing 2 1/2 continuous fills of
my original tank.

But assuming that I am careful about duty cycle is this a reasonable way
to temporarily extend the initial air supply for occassional uses where
I need to get the advantages of a larger tank?

(Note that it seems that several of the Harbor Freight compressors use
the same HP motor with similar CFM ratings for a range of tank sizes --
probably because the HP is ultimately limited by the 110V 15A supply
circuit)

Thanks!

Yes, your idea will be useful in application you describe (blow out
sprinkler system)

I did some "back of the envelop" calcs.

Assuming a sprinkler zone has about 100ft of 3/4" PVC pipe & zone's
total flow is about 15 gpm.

Actually it's about 10gpm per zone (for each of 9 zones).

Charge your compressed air tanks to maximum pressure
but I'd recommend using a pressure regulator in the supply hose to the
sprinkler system.....set at no higher than 50 psi.

That is exactly what I have been doing the past 7 years.

PVC piping is not meant to be used with compressed air.. ...... there
is a danger of brittle failure.
Safety glasses & cleared area are highly recommended.

Your original compressor setup will blow out a single zone for about
25 secs ....kinda short.

I get about 30-40 seconds. So your calculations are on target.

Add the 11 gallon tank & bump your total storage to 19 gallons, you
can blow out a single zone for about 70 secs.
Two blown outs per zone should do the trick.

Currently, I get a good blowout (only steam) after about 3-4 tankfulls
@8 gallons. I do about 6-7 runs just to be sure.

I was hoping with 19 gallons to get 60+ seconds per run so that the runs
are both longer and better (less 'wasted' air just opening up the heads
and filling the system as a fraction of the run time). My thinking was I
could do it then in 3-4 runs with a good margin of safety.

I'd plumb the tanks together with 1/2" pipe minimum and use Ed'
suggestion of a valve between the tanks.

That was already in my plan...

You can use the valve to select total compressed air volume and
control duty cycle.


I actually first built an electronic circuit using a 555 timer to
control the valve to get me an adjustable on/off pulse width. Currently,
I let it discharge for about a minute and then close for about 4
minutes. Since the tank fills in about 1.5 minutes, I have an
approximate compressor duty cycle of 33%.

Last year, I hacked my controller to be able to run it via a
plugcomputer, so now I can use simple bash shell scripts to open and
close the valves at any interval and in any order I want. I can even
control it over my phone using sms messages or remotely via any laptop
over wifi.

Finally, I position a portable fan near the compressor motor and housing
to give it some extra cooling...

"Mike Marlow" writes:

DD_BobK wrote:


PVC piping is not meant to be used with compressed air.. ...... there
is a danger of brittle failure.
Safety glasses & cleared area are highly recommended.


This should not be an issue for him since the PVC lines are open and he's
blowing air through them - correct? It's not like he's charging those
lines.

I use a regulator to keep the pressure at about 40-50 psi...

Leon lcb11211@swbelldotnet writes:

On 10/24/2011 2:25 AM, DD_BobK wrote:
On Oct 23, 5:48 pm, wrote:
I have a low-end Harbor Freight 8 gallon air compressor that has many
times over earned its $100 cost.

However, there are times when I would like to have a larger air supply
tank such as when I am blowing out my irrigation system. Of course the
steady-state is limited by the compressor motor to about 4-5 CFM@90 psi.

But I was wondering whether I could extend at least the initial volume
by adding an additional tank.

Harbor Freight for example sells an 11 gallon portable air tank
(http://www.harborfreight.com/11-gall...ank-65595.html)
for about $38. It is rated up to 125 psi (same as my compressor) and
comes with a gauge and a tire-type fitting.

I was thinking that I could re-plumb to NPT and attach it to the drain
hole on my compressor tank (with a T-fitting and ball valve to still
allow drainage).

This would then give me effectively 19 gallons of initial air supply.

Of course, I would need to be careful about duty cycle since filling up
19 gallons vs. 8 gallons would be like doing 2 1/2 continuous fills of
my original tank.

But assuming that I am careful about duty cycle is this a reasonable way
to temporarily extend the initial air supply for occassional uses where
I need to get the advantages of a larger tank?

(Note that it seems that several of the Harbor Freight compressors use
the same HP motor with similar CFM ratings for a range of tank sizes --
probably because the HP is ultimately limited by the 110V 15A supply
circuit)

Thanks!

Yes, your idea will be useful in application you describe (blow out
sprinkler system)

I did some "back of the envelop" calcs.

Assuming a sprinkler zone has about 100ft of 3/4" PVC pipe& zone's
total flow is about 15 gpm.

Charge your compressed air tanks to maximum pressure
but I'd recommend using a pressure regulator in the supply hose to the
sprinkler system.....set at no higher than 50 psi.

PVC piping is not meant to be used with compressed air.. ...... there
is a danger of brittle failure.
Safety glasses& cleared area are highly recommended.

Your original compressor setup will blow out a single zone for about
25 secs ....kinda short.

Add the 11 gallon tank& bump your total storage to 19 gallons, you
can blow out a single zone for about 70 secs.
Two blown outs per zone should do the trick.

I'd plumb the tanks together with 1/2" pipe minimum and use Ed'
suggestion of a valve between the tanks.
You can use the valve to select total compressed air volume and
control duty cycle.

cheers
Bob

Did you calculate for the fact that pushing a liquid "up" requires a
lot of continuous air flow? And concerning your blow time, how much
of that is way below 50 psi which would be much less effective?
From some that did this for a living he would run the compressed air
at a continuous pressure for 10 -15 minutes. And calculations for
100' might be correct but I had a small yard and probably had 250' of
underground line on one run, not to mention all the heads that are
leaking air.

All I can say is that it works for me... and after a few tank fulls it
is just blowing steam (not even mist) -- just humidified air.

Even if there are some residual drops somewhere in the line, there is
now enough air and expansion space in the system to prevent any ruptures
when the tiny residual water (if any) freezes...

On Oct 23, 11:26*pm, Puckdropper puckdropper(at)yahoo(dot)com wrote:
!

Where it might make a difference is in air hungry intermittent duty
tools like air wrenches. *The extra reserve of air would allow the tool
to run longer (perhaps enough to finish the job) before the compressor
kicks on.

If you do this, make sure to open the compressor regulator to charge the
tank fully and then put another regulator before the tool connection.
If all you charge the tank with is 30 psi, you won't see much difference
at all. *Charge to 100 or 120 psi and you'll notice the difference.

Exactly my experience. When I spray finish with an hvlp conversion
gun, the pressure moves too far up and down to get a completely
consistent flow to the gun. The extra storage of the tank give me
more compressed air available at once.

I turn up the compressor side to 100 psi, and pressure the tank and
the second tank. On the downside (line to gun connection from the
pony tank) I have a line conditioner/water removal regulator combo
that I set at 50psi. Gun is fine tuned as needed wit another gauge at
the handle to about 30 - 40 depending on the material and conditions.

Having that much volume of 100 psi air metered out at 50 psi (some fan
of Bernoulli can figure out the exact benefit) and ultimately a little
less than that made a world of difference in spraying. I can spray
much longer without line pressure drop, and if i can see it by the
quality of spray deteriorating as it comes out of the gun I simply
bleed off the remaining air needed to kick the machine to on to
recharge the two tanks. Wait a couple of minutes and I am back in
business with a lot of newly compressed, consistently pressured air.

For a couple of cab doors and a drawer or two, the compressor never
starts up, and I am finished.

To the OP, as far as cleaning out pipes is concerned, I think you
would have about the same effect. A lot higher volume of compressed
air initially, but to benefit you would have to let the tank charge up
each time to charge both tanks after you depleted them. I am thinking
that if your system is working now, don't screw with it. And heck, at
$38, you are almost half way to a while new compressor from HF!

Robert

On Oct 24, 4:57*am, Leon lcb11211@swbelldotnet wrote:
On 10/24/2011 2:25 AM, DD_BobK wrote:









On Oct 23, 5:48 pm, *wrote:
I have a low-end Harbor Freight 8 gallon air compressor that has many
times over earned its $100 cost.

However, there are times when I would like to have a larger air supply
tank such as when I am blowing out my irrigation system. Of course the
steady-state is limited by the compressor motor to about 4-5 CFM@90 psi.

But I was wondering whether I could extend at least the initial volume
by adding an additional tank.

Harbor Freight for example *sells an 11 gallon portable air tank
(http://www.harborfreight.com/11-gall...ank-65595.html)
for about $38. It is rated up to 125 psi (same as my compressor) and
comes with a gauge and a tire-type fitting.

I was thinking that I could re-plumb to NPT and attach it to the drain
hole on my compressor tank (with a T-fitting and ball valve to still
allow drainage).

This would then give me effectively 19 gallons of initial air supply.

Of course, I would need to be careful about duty cycle since filling up
19 gallons vs. 8 gallons would be like doing 2 1/2 continuous fills of
my original tank.

But assuming that I am careful about duty cycle is this a reasonable way
to temporarily extend the initial air supply for occassional uses where
I need to get the advantages of a larger tank?

(Note that it seems that several of the Harbor Freight compressors use
the same HP motor with similar CFM ratings for a range of tank sizes --
probably because the HP is ultimately limited by the 110V 15A supply
circuit)

Thanks!

Yes, your idea will be useful in application you describe (blow out
sprinkler system)

I did some "back of the envelop" calcs.

Assuming a sprinkler zone has about 100ft of 3/4" PVC pipe& *zone's
total flow is about 15 gpm.

Charge your compressed air tanks to maximum pressure
but I'd recommend using a pressure regulator in the supply hose to the
sprinkler system.....set at no higher than 50 psi.

PVC piping is not meant to be used with compressed air.. ...... there
is a danger of brittle failure.
Safety glasses& *cleared area are highly recommended.

Your original compressor setup will blow out a single zone for about
25 secs ....kinda short.

Add the 11 gallon tank& *bump your total storage to 19 gallons, you
can blow out a single zone for about 70 secs.
Two blown outs per zone should do the trick.

I'd plumb *the tanks together with 1/2" pipe minimum and use Ed'
suggestion of a valve between the tanks.
You can use the valve to select total compressed air volume and
control duty cycle.

cheers
Bob

Did you calculate for the fact that pushing a liquid "up" requires a lot
of continuous air flow? *And concerning your blow time, how much of that
is way below 50 psi which would be much less effective?
*From some that did this for a living he would run the compressed air at
a continuous pressure for 10 -15 minutes. *And calculations for 100'
might be correct but I had a small yard and probably had 250' of
underground line on one run, not to mention all the heads that are
leaking air.

Leon-

My calcs's & sprinkler zone design were merely SWAGS......... .

I've done I fair number of sprinkler systems (new & rework)....never
seen 250' on a single zone with 3/4" pipe.
I had a hard time seeing his system from my keyboard so I guessed.

Read my post...all of my blow out is with the tanks at 50 psi or
higher.

The task at hand was to evaluate his idea of adding 11 gallons of
reservoir volume not determine optimum blow out compressor size & blow
out.

As I said my calc's & assumptions were SWAGS...... and based on
blueman's followup posts, they appear to be "in the ballpark".
The addtiotnal informatin he provided also seem to confirm that the
added 11 gallons & the way he intends to plumb up the addition will
result is system that does the job for me.

Mission accomplished?

cheers
Bob

On Oct 24, 4:55*am, "Mike Marlow"
wrote:
DD_BobK wrote:

PVC piping is not meant to be used with compressed air.. ...... there
is a danger of brittle failure.
Safety glasses & cleared area are highly recommended.

This should not be an issue for him since the PVC lines are open and he's
blowing air through them - correct? *It's not like he's charging those
lines.

--

-Mike-


Yes...you are correct but I believe it is always good to remind people
that PVC is not meant for use with compressed gases.

falls under the heading " ..... happens"

cheers
Bob

In ,
blueman typed:
I have a low-end Harbor Freight 8 gallon air compressor
that has many times over earned its $100 cost.

However, there are times when I would like to have a
larger air supply tank such as when I am blowing out my
irrigation system. Of course the steady-state is limited
by the compressor motor to about 4-5 CFM@90 psi.

But I was wondering whether I could extend at least the
initial volume by adding an additional tank.

Harbor Freight for example sells an 11 gallon portable
air tank
(http://www.harborfreight.com/11-gall...ank-65595.html)
for about $38. It is rated up to 125 psi (same as my
compressor) and comes with a gauge and a tire-type
fitting.

I was thinking that I could re-plumb to NPT and attach it
to the drain hole on my compressor tank (with a T-fitting
and ball valve to still allow drainage).

This would then give me effectively 19 gallons of initial
air supply.

Of course, I would need to be careful about duty cycle
since filling up 19 gallons vs. 8 gallons would be like
doing 2 1/2 continuous fills of my original tank.

But assuming that I am careful about duty cycle is this a
reasonable way to temporarily extend the initial air
supply for occassional uses where I need to get the
advantages of a larger tank?

(Note that it seems that several of the Harbor Freight
compressors use the same HP motor with similar CFM
ratings for a range of tank sizes -- probably because the
HP is ultimately limited by the 110V 15A supply circuit)

Thanks!

Simply put, you'll get a longer run time and a longer tank-fill time. Your
plan sounds fine as is.

HTH,

Twayne`

blueman writes:

I have a low-end Harbor Freight 8 gallon air compressor that has many
times over earned its $100 cost.

However, there are times when I would like to have a larger air supply
tank such as when I am blowing out my irrigation system. Of course the
steady-state is limited by the compressor motor to about 4-5 CFM@90 psi.

But I was wondering whether I could extend at least the initial volume
by adding an additional tank.

Harbor Freight for example sells an 11 gallon portable air tank
(http://www.harborfreight.com/11-gall...ank-65595.html)
for about $38. It is rated up to 125 psi (same as my compressor) and
comes with a gauge and a tire-type fitting.

I was thinking that I could re-plumb to NPT and attach it to the drain
hole on my compressor tank (with a T-fitting and ball valve to still
allow drainage).

This would then give me effectively 19 gallons of initial air supply.

Of course, I would need to be careful about duty cycle since filling up
19 gallons vs. 8 gallons would be like doing 2 1/2 continuous fills of
my original tank.

But assuming that I am careful about duty cycle is this a reasonable way
to temporarily extend the initial air supply for occassional uses where
I need to get the advantages of a larger tank?

(Note that it seems that several of the Harbor Freight compressors use
the same HP motor with similar CFM ratings for a range of tank sizes --
probably because the HP is ultimately limited by the 110V 15A supply
circuit)

Thanks!

Now that a new Harbor Freight has opened up about 9 miles, I went to the
store and bought the tank for $37, an 8 ft 3/8" 200psi hose on sale for
$4 and a couple of fittings for a few bucks. And I used a 20% coupon on
the entire purchase...

So for less than $40 total, I have it all working beautifully.

The setup now looks like:


Portable tank------- Tee --- 3/8" hose -- Female quick connect
| |
Gauge Ball valve
& pressure release
(included)

(Note: I added the ball valve to allow for easy emptying rather than
having to exert constant pressure on the built in release


Compressor ---- Drain --- Ball valve --- Male quick connect



When I want to fill the external tank, I quick connect from the tank to
the drain, open the ball valve on the compressor drain and close the
ball valve on the tank.

Then if I want to use the combined volume, I just attach my hoses and
tools to the normal regulator side of my compressor and get a combined
19 gallon volume

If I want to use the portable tank remotely, I just disconnect the quick
connect and then connect hoses and tools to the female quick connect on
the portable tank (I may add an inline regulator later).

If I want to drain both tanks, then I disconnect the quick connect and
open the ball valves on both the compressor tank and the portable tank.


Thanks for all the helpful comments that gave me the confidence to go
ahead with my plan.

Now I just have to wait a few weeks until it's time to blow out my
irrigation system.

Also, as a few others have mentioned, it will be good for high volume,
relatively limited time operations like HVLP spraying.

On 10/24/2011 6:40 PM, blueman wrote:
writes:


Now I just have to wait a few weeks until it's time to blow out my
irrigation system.

Be sure to report back and let us know how much difference it made.

--
www.eWoodShop.com
Last update: 4/15/2010
KarlCaillouet@ (the obvious)
http://gplus.to/eWoodShop

BTW I clear my pool lines using my shop vac. That really pushes quite a
bit through. I realize that my 1.5 inch lines don't compare to a 1" line.
But you might consider it. make an adapter using pvc and a step down.
It might be the ticket.

On 10/24/2011 11:51 AM, blueman wrote:
Ed writes:

On Sun, 23 Oct 2011 20:48:18 -0400, wrote:

I have a low-end Harbor Freight 8 gallon air compressor that has many
times over earned its $100 cost.

However, there are times when I would like to have a larger air supply
tank such as when I am blowing out my irrigation system. Of course the
steady-state is limited by the compressor motor to about 4-5 CFM@90 psi.

But I was wondering whether I could extend at least the initial volume
by adding an additional tank.


There are numerous ways to pipe the tank in line. Your reasoning is
correct, you get the initial burst, but that is all.

I'd pipe it in, but I'd put a valve in the line to shut it off. Two
reasons for that. There is no good reason to fill that tank if you
are not going to need the backup of air. Saves both time and energy
at startup for normal work.

Second, you can fill it, close the valve, and have it ready for use.
You can also open the valve and use that air if you only need a little
shot of it and not have to start the compressor.

All good points -- I actually am planning on doing that for all the
reasons you mention...

tiredofspam nospam.nospam.com writes:
BTW I clear my pool lines using my shop vac. That really pushes quite
a bit through. I realize that my 1.5 inch lines don't compare to a 1"
line.
But you might consider it. make an adapter using pvc and a step down.
It might be the ticket.


Interesting. I use my shop vac in blower mode to go through 20-30ft of
2" PVC to reach & blow out the gutters on my 3rd floor roof. It works
well.

I guess the question would be what type of pressure could a shop vac
push through 100-150 feet of 1" pvc irrigation tubing. Also the
sprinkler heads & rotors along with the backflow preventer all require a
certain minimal pressure to operate plus you need enough force to flush out
the water.

Sort of the opposite problem of a compressor where you have plenty of
pressure but lack volume; here you have plenty of volume but may lack
pressure...

On Mon, 24 Oct 2011 19:40:31 -0400, blueman wrote:


However, there are times when I would like to have a larger air supply
tank such as when I am blowing out my irrigation system. Of course the
steady-state is limited by the compressor motor to about 4-5 CFM@90 psi.

I am in the same situation. I also thought about the exact same tank.
Last year I paid the $20 for a commercial blow job. His compressor
put out 100 CFM. It took several minutes for the remote heads to stop
blowing mist. My observation is the 8 gallons of air will blow out
the near heads and is exhausted in a few seconds, another 11 gallons
may extend this to a fraction of a minute. The consensus on the
Internet is a min of 10 to 15 CFM is required. This somewhat depends
on the slope of the lawn. The steeper the slope the more CFM
required. In a previous house with a flatter lawn and auto drains at
the low spots I used my small compressor for years with no problem.

Next I thought about the $129 HF 6 CFM in conjunction with my present
compressor. It is close, but I am not sure if my expected lifetime
would justify this expense.

So my solution this year was to blow out and use a shop vac to
evacuate the far heads. After doing that I decided to hire the pro
next year. Tomorrow it is going to be 14 so I hope I got enough water
out. A little water in the poly pipe won't cause a problem, sprinkler
heads are cheap, the expensive anti siphon is water free.

Lets us know how you make out.

On 10/23/2011 5:48 PM, blueman wrote:
I have a low-end Harbor Freight 8 gallon air compressor that has many
times over earned its $100 cost.

However, there are times when I would like to have a larger air supply
tank such as when I am blowing out my irrigation system. Of course the
steady-state is limited by the compressor motor to about 4-5 CFM@90 psi.

But I was wondering whether I could extend at least the initial volume
by adding an additional tank.

Harbor Freight for example sells an 11 gallon portable air tank
(http://www.harborfreight.com/11-gall...ank-65595.html)
for about $38. It is rated up to 125 psi (same as my compressor) and
comes with a gauge and a tire-type fitting.

I was thinking that I could re-plumb to NPT and attach it to the drain
hole on my compressor tank (with a T-fitting and ball valve to still
allow drainage).

This would then give me effectively 19 gallons of initial air supply.

Of course, I would need to be careful about duty cycle since filling up
19 gallons vs. 8 gallons would be like doing 2 1/2 continuous fills of
my original tank.

But assuming that I am careful about duty cycle is this a reasonable way
to temporarily extend the initial air supply for occassional uses where
I need to get the advantages of a larger tank?

(Note that it seems that several of the Harbor Freight compressors use
the same HP motor with similar CFM ratings for a range of tank sizes --
probably because the HP is ultimately limited by the 110V 15A supply
circuit)

Thanks!


Absolutely reasonable thing to do. My son does exactly this when he
blows out his irrigation system. A "T" and some extra couplers then
3/8" hose from the extra tank to the blow point.

--
Steve Barker
remove the "not" from my address to email

On Oct 25, 11:32*am, Ray wrote:
On Mon, 24 Oct 2011 19:40:31 -0400, blueman wrote:

"Last year I paid the $20 for a commercial blow job."

Where do you go to get such a low price?

On Wed, 26 Oct 2011 13:39:38 -0700 (PDT), Hoosierpopi
wrote:

On Oct 25, 11:32*am, Ray wrote:
On Mon, 24 Oct 2011 19:40:31 -0400, blueman wrote:

"Last year I paid the $20 for a commercial blow job."
Where do you go to get such a low price?

If it was commercial, it probably was mechanized. Vacuum maybe?

On Wed, 26 Oct 2011 13:39:38 -0700 (PDT), Hoosierpopi
wrote:

On Oct 25, 11:32*am, Ray wrote:
On Mon, 24 Oct 2011 19:40:31 -0400, blueman wrote:

"Last year I paid the $20 for a commercial blow job."

Where do you go to get such a low price?

I was done with a trailer mounted compressor in northern Colorado.
Simple 4 zone system. It took less than 15 minutes, or $80 per hour.
What is a fair price?

Ray writes:

On Mon, 24 Oct 2011 19:40:31 -0400, blueman wrote:


However, there are times when I would like to have a larger air supply
tank such as when I am blowing out my irrigation system. Of course the
steady-state is limited by the compressor motor to about 4-5 CFM@90 psi.

I am in the same situation. I also thought about the exact same tank.
Last year I paid the $20 for a commercial blow job.

Around here (big East Coast urban area), I was charged $75 to blow out
my 9 zone system, back SEVEN years ago. I imagine now it might be $100.
So, doing it myself has already paid for my trusty HF compressor 5 times
over...

His compressor put out 100 CFM. It took several minutes for the
remote heads to stop blowing mist.

The one time I went professional, he did 4-5 zones at a time (we have a
9 zone system), so even if had a 100 CFM system (which I'm not sure is
even possible to push through a 100 ft of 1" PVC feed pipe at a PSI of
50), we are talking only about 20-25 CFM per zone

air will blow out the near heads and is exhausted in a few seconds,
another 11 gallons may extend this to a fraction of a minute. The
consensus on the Internet is a min of 10 to 15 CFM is required. This
somewhat depends on the slope of the lawn. The steeper the slope the
more CFM required. In a previous house with a flatter lawn and auto
drains at the low spots I used my small compressor for years with no
problem.

Well, consensus doesn't equal experience. People told me the same thing
7 years ago, when I inquired. But my 8 gallon HF compressor which is
rated at 7.25 SCFM@40 PSI has done just fine.

I do each zone separately, blowing it out 5-6 times just to be sure,
though it starts blowing pure mist after about 2-3 times. Some of the
zones are on a mild hill. Each zone has 4-7 heads which together deliver
about 10gpm. The run lengths to the heads are about 100ft. When there is
still water in the tubing, I get effective pressure for about 45
seconds. When it's just misting, I get about 25-30 seconds of good
pressue (enough to lift heads & turn the rotors). By adding an 11 gallon
external tank which will bump my capacity from 8 to 19 gallons, I expect
to get over a minute per cycle of effective pressure.

As I mentioned in another post, I use either a home-built electronic
timer or a hacked computer remote control to automate the process. I go
slow to allow the compressor time to cool down between bursts so the
whole process takes several hours -- but it all runs automatically so it
takes almost none of my time.



Next I thought about the $129 HF 6 CFM in conjunction with my present
compressor. It is close, but I am not sure if my expected lifetime
would justify this expense.

So my solution this year was to blow out and use a shop vac to
evacuate the far heads. After doing that I decided to hire the pro
next year. Tomorrow it is going to be 14 so I hope I got enough water
out. A little water in the poly pipe won't cause a problem, sprinkler
heads are cheap, the expensive anti siphon is water free.

Lets us know how you make out.

Well I guess if I only paid $20 for a blowout, it would be worth it to
have someone else do it even though it's only a few minutes of work with
my setup now. But I don't know how anyone can come to your house for $20
nowadays given the cost of gas etc. I mean repair people often charge
$100 just to cross your threshhold...

Ray writes:

On Wed, 26 Oct 2011 13:39:38 -0700 (PDT), Hoosierpopi
wrote:

On Oct 25, 11:32Â*am, Ray wrote:
On Mon, 24 Oct 2011 19:40:31 -0400, blueman wrote:

"Last year I paid the $20 for a commercial blow job."

Where do you go to get such a low price?

I was done with a trailer mounted compressor in northern Colorado.
Simple 4 zone system. It took less than 15 minutes, or $80 per hour.
What is a fair price?

Well, they do have to drive back and forth to your house. Even if they
do several houses in a neighborhood, I can't imagine that they can
reliably schedule more than 2-3 per hour which means $40-60 per
hour. For that you have to pay the person, overhead, insurance, truck,
equipment, gas, etc.

Steve Barker writes:

On 10/23/2011 5:48 PM, blueman wrote:
I have a low-end Harbor Freight 8 gallon air compressor that has many
times over earned its $100 cost.

However, there are times when I would like to have a larger air supply
tank such as when I am blowing out my irrigation system. Of course the
steady-state is limited by the compressor motor to about 4-5 CFM@90 psi.

But I was wondering whether I could extend at least the initial volume
by adding an additional tank.

Harbor Freight for example sells an 11 gallon portable air tank
(http://www.harborfreight.com/11-gall...ank-65595.html)
for about $38. It is rated up to 125 psi (same as my compressor) and
comes with a gauge and a tire-type fitting.

I was thinking that I could re-plumb to NPT and attach it to the drain
hole on my compressor tank (with a T-fitting and ball valve to still
allow drainage).

This would then give me effectively 19 gallons of initial air supply.

Of course, I would need to be careful about duty cycle since filling up
19 gallons vs. 8 gallons would be like doing 2 1/2 continuous fills of
my original tank.

But assuming that I am careful about duty cycle is this a reasonable way
to temporarily extend the initial air supply for occassional uses where
I need to get the advantages of a larger tank?

(Note that it seems that several of the Harbor Freight compressors use
the same HP motor with similar CFM ratings for a range of tank sizes --
probably because the HP is ultimately limited by the 110V 15A supply
circuit)

Thanks!


Absolutely reasonable thing to do. My son does exactly this when he
blows out his irrigation system. A "T" and some extra couplers then
3/8" hose from the extra tank to the blow point.

Well, I actually connected it to the tank directly (via the drain hole)
so it goes before the regulator and insures both tanks are filled to
full pressure...

Ray writes:

On Mon, 24 Oct 2011 19:40:31 -0400, blueman wrote:


However, there are times when I would like to have a larger air supply
tank such as when I am blowing out my irrigation system. Of course the
steady-state is limited by the compressor motor to about 4-5 CFM@90 psi.

I am in the same situation. I also thought about the exact same tank.
Last year I paid the $20 for a commercial blow job. His compressor
put out 100 CFM. It took several minutes for the remote heads to stop
blowing mist. My observation is the 8 gallons of air will blow out
the near heads and is exhausted in a few seconds, another 11 gallons
may extend this to a fraction of a minute. The consensus on the
Internet is a min of 10 to 15 CFM is required. This somewhat depends
on the slope of the lawn. The steeper the slope the more CFM
required. In a previous house with a flatter lawn and auto drains at
the low spots I used my small compressor for years with no problem.

One more point, with 19 gallons (8+11) at 115psi, this gives 54 gallons
at 40 psi for the initial bolus -- which should be enough to fill any
reasonable residential style irrigation zone..

On Thu, 27 Oct 2011 12:48:58 -0400, blueman wrote:

Ray writes:


I do each zone separately, blowing it out 5-6 times just to be sure,
though it starts blowing pure mist after about 2-3 times. Some of the
zones are on a mild hill. Each zone has 4-7 heads which together deliver
about 10gpm. The run lengths to the heads are about 100ft. When there is
still water in the tubing, I get effective pressure for about 45
seconds. When it's just misting, I get about 25-30 seconds of good
pressue (enough to lift heads & turn the rotors). By adding an 11 gallon
external tank which will bump my capacity from 8 to 19 gallons, I expect
to get over a minute per cycle of effective pressure.

Thanks for the input. I am half considering buying the 6CFM HF $129
compressor so I can do it myself and don't have to hassle with the air
compressor people. My configuration is different from yours. I have
9 sprinkler heads on a zone. The 3 heads at the end of the run are
about 10 feet below the other 6 heads. The first two blasts of air
will clear the higher up 6 heads. After that the blasts loose the
pressure in the clear heads and I can't seem to build the pressure on
the 3 low heads. I vacuumed the lower heads and got just over a cup
of water. I am not sure that this would cause much damage. I am in
my 70's so I am not sure how much longer I will be up to this.


Any further insight would be appreciated.



Well I guess if I only paid $20 for a blowout, it would be worth it to
have someone else do it even though it's only a few minutes of work with
my setup now. But I don't know how anyone can come to your house for $20
nowadays given the cost of gas etc. I mean repair people often charge
$100 just to cross your threshhold...

This year the price was up to $25. There are also a lot of people
doing lawn aeration for $25. That seems like a lot more work than a
blowout. Times are tough and a lot of people looking to make a few
bucks.

He was thinking out loud just like you just did.

When you achieve perfection, let us know how you did it.

------------

"Mike Marlow" wrote in message
...

P.H. T. wrote:
Don't know if that is possible. I don't know who makes that Harbor
Freight that you have, but if they have a U.S. number, I would call
them and talk to them about doing that. Or talk to someone local that
knows air compressor's and could guide you on that.

Paul T.



Yes - it is very possible. Why would anyone respond with "I don't know
if
that is possible"? Hell - better to watch the responses and see.
Possible
is one thing - probable is quite another.

--

-Mike-

On 10/27/2011 7:42 PM, Ray wrote:
On Thu, 27 Oct 2011 12:48:58 -0400, wrote:

writes:


I do each zone separately, blowing it out 5-6 times just to be sure,
though it starts blowing pure mist after about 2-3 times. Some of the
zones are on a mild hill. Each zone has 4-7 heads which together deliver
about 10gpm. The run lengths to the heads are about 100ft. When there is
still water in the tubing, I get effective pressure for about 45
seconds. When it's just misting, I get about 25-30 seconds of good
pressue (enough to lift heads& turn the rotors). By adding an 11 gallon
external tank which will bump my capacity from 8 to 19 gallons, I expect
to get over a minute per cycle of effective pressure.

Thanks for the input. I am half considering buying the 6CFM HF $129
compressor so I can do it myself and don't have to hassle with the air
compressor people. My configuration is different from yours. I have
9 sprinkler heads on a zone. The 3 heads at the end of the run are
about 10 feet below the other 6 heads. The first two blasts of air
will clear the higher up 6 heads. After that the blasts loose the
pressure in the clear heads and I can't seem to build the pressure on
the 3 low heads. I vacuumed the lower heads and got just over a cup
of water. I am not sure that this would cause much damage. I am in
my 70's so I am not sure how much longer I will be up to this.


Any further insight would be appreciated.

put a drain at the lowest end.



Well I guess if I only paid $20 for a blowout, it would be worth it to
have someone else do it even though it's only a few minutes of work with
my setup now. But I don't know how anyone can come to your house for $20
nowadays given the cost of gas etc. I mean repair people often charge
$100 just to cross your threshhold...

This year the price was up to $25. There are also a lot of people
doing lawn aeration for $25. That seems like a lot more work than a
blowout. Times are tough and a lot of people looking to make a few
bucks.