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Default How much PSI can this pump produce?

I have a Magnetek 1081 PB4 Booster Pump, 3/4 hp, 3450 rpm - part
#173840-20 attached to my pool to run a pool cleaner. I don't have the
official specs for it so would anyone know how to calculate how much PSI
this pump can/should produce?

Thank you.
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Default How much PSI can this pump produce?


"Stuart Benoff" wrote in message
...
I have a Magnetek 1081 PB4 Booster Pump, 3/4 hp, 3450 rpm - part
#173840-20 attached to my pool to run a pool cleaner. I don't have the
official specs for it so would anyone know how to calculate how much PSI
this pump can/should produce?

Thank you.


I think most pumps are rated Gallons per minute GPM. pool system run at
a very low PSI 10 to 20.


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Default How much PSI can this pump produce?

Sacramento Dave wrote:
"Stuart Benoff" wrote in message
...

I have a Magnetek 1081 PB4 Booster Pump, 3/4 hp, 3450 rpm - part
#173840-20 attached to my pool to run a pool cleaner. I don't have the
official specs for it so would anyone know how to calculate how much PSI
this pump can/should produce?

Thank you.



I think most pumps are rated Gallons per minute GPM. pool system run at
a very low PSI 10 to 20.



That's interesting because the cleaner that it's attached to says that
it needs between 20 and 25 PSI for it to be completely effective. You'd
think that they would say between X and Y GPM?
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Default How much PSI can this pump produce?


"Stuart Benoff" wrote in message
...
I have a Magnetek 1081 PB4 Booster Pump, 3/4 hp, 3450 rpm - part
#173840-20 attached to my pool to run a pool cleaner. I don't have the
official specs for it so would anyone know how to calculate how much PSI
this pump can/should produce?

Thank you.


Pressure gauge in the line


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Default How much PSI can this pump produce?

According to Stuart Benoff :
Sacramento Dave wrote:
"Stuart Benoff" wrote in message
...

I have a Magnetek 1081 PB4 Booster Pump, 3/4 hp, 3450 rpm - part
#173840-20 attached to my pool to run a pool cleaner. I don't have the
official specs for it so would anyone know how to calculate how much PSI
this pump can/should produce?

Thank you.



I think most pumps are rated Gallons per minute GPM. pool system run at
a very low PSI 10 to 20.


That's interesting because the cleaner that it's attached to says that
it needs between 20 and 25 PSI for it to be completely effective. You'd
think that they would say between X and Y GPM?


Flow rate is dependent on PSI, so they pick the one that's of most
importance to the device to spec it. This device cares more about
pressure than flow rate.

With a freshly cleaned sand filter, my pool pump produces about
15PSI on the manifold's pressure guage. As the sand filter
gunks up, the pressure rises.

My pump will produce about 35PSI if the outlet is completely plugged.

[We've tee'd the discharge system into a fire hose. If you shut
the fire hose's nozzle off, pump pressure hits 35PSI.]
--
Chris Lewis, Una confibula non set est
It's not just anyone who gets a Starship Cruiser class named after them.


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Default How much PSI can this pump produce?

Chris Lewis wrote:
According to Stuart Benoff :

Sacramento Dave wrote:

"Stuart Benoff" wrote in message
...


I have a Magnetek 1081 PB4 Booster Pump, 3/4 hp, 3450 rpm - part
#173840-20 attached to my pool to run a pool cleaner. I don't have the
official specs for it so would anyone know how to calculate how much PSI
this pump can/should produce?

Thank you.


I think most pumps are rated Gallons per minute GPM. pool system run at
a very low PSI 10 to 20.




That's interesting because the cleaner that it's attached to says that
it needs between 20 and 25 PSI for it to be completely effective. You'd
think that they would say between X and Y GPM?



Flow rate is dependent on PSI, so they pick the one that's of most
importance to the device to spec it. This device cares more about
pressure than flow rate.

With a freshly cleaned sand filter, my pool pump produces about
15PSI on the manifold's pressure guage. As the sand filter
gunks up, the pressure rises.

My pump will produce about 35PSI if the outlet is completely plugged.

[We've tee'd the discharge system into a fire hose. If you shut
the fire hose's nozzle off, pump pressure hits 35PSI.]


I'm trying to determine if there is a problem with the pump. When I put
a pressure gauge on the line it reads 14-15 PSI however, this is a
'booster' pump not the mail pool pump. It's designed to send
pressurized water to the pool cleaner. The cleaner requires 20-25 PSI
and recommended a pump of this size. So, I'm trying to determine if the
pump is undersized or whether or not there's a problem with the pump.
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Default How much PSI can this pump produce?

According to Stuart Benoff :

I'm trying to determine if there is a problem with the pump. When I put
a pressure gauge on the line it reads 14-15 PSI however, this is a
'booster' pump not the mail pool pump. It's designed to send
pressurized water to the pool cleaner. The cleaner requires 20-25 PSI
and recommended a pump of this size. So, I'm trying to determine if the
pump is undersized or whether or not there's a problem with the pump.


The question is whether the booster pump reads 14-15 PSI _with_ the
pool cleaner attached. Does it? Or are you measuring the pressure
without the pool cleaner attached with the pump discharging some other
way? Are you measuring the pressure at the pump or at the cleaner?
Try attaching the cleaner and _then_ see what the PSI is at _both_
the pump and cleaner ends.

[I'm not familiar with the use of pool cleaners working on the
pressure side of the pump. It _may_ also be that your plumbing is
undersized or restricted. In which case, the PSI at the pump
end will be okay, but at the cleaner end it won't be.]

Think of it this way - a device like the pool cleaner needs to be
specified at a specific pressure AND flow rate. Eg: "to operate
properly, this device needs 1GPM or more at a pressure of 15PSI
or more".

Secondly, the plumbing between the two devices matter - it has
to be large enough to permit the GPMs that the cleaner needs
without excessive PSI loss.

Industrial equipment is rated/matched that way. So are, for example,
tools for use with air compressors (eg: "this tool consumes
x CFM at y PSI").

The PSI of the output of a pump varies inversely with the GPM
the outlet is permitting.

Pumps _tend_ to have a given "PSI vs GPM" curve given the
HP rating of the pump. In the middle "design range" (of GPMs),
it's pretty much determined by the HP of the pump.

It's not linear, but at least for the most part, two pumps with
the same HP rating _should_ push just about the same amount of GPMs
at the same PSI as each other.

So, if it's the right HP, it (probably) _should_ work.

But, without knowing the GPM requirements of the cleaner or the expected
GPM vs PSI curve of the pump, it's difficult to be absolutely certain
whether a given combination _should_ work or not, and the best bet is
probably to call the manufacturer[s] (cleaner manufacturer _first_),
explain your situation mentioning model numbers etc, and they should be
able to tell you whether the cleaner or the pump are working in spec or not.

The cleaner manufacturer is probably intimately familiar with the
behaviour of the cleaner with every pump on the market. If they
tell you "we have lots of cleaner customers using that pump
satisfactorily", you _know_ that something's wrong with one
(or both) of the devices. They may tell you that there's
something specifically "odd" about that pump that means it won't
work. Or they may tell you that the plumbing is too small.
--
Chris Lewis, Una confibula non set est
It's not just anyone who gets a Starship Cruiser class named after them.
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Default How much PSI can this pump produce?

Chris Lewis wrote:
According to Stuart Benoff :


I'm trying to determine if there is a problem with the pump. When I put
a pressure gauge on the line it reads 14-15 PSI however, this is a
'booster' pump not the mail pool pump. It's designed to send
pressurized water to the pool cleaner. The cleaner requires 20-25 PSI
and recommended a pump of this size. So, I'm trying to determine if the
pump is undersized or whether or not there's a problem with the pump.



The question is whether the booster pump reads 14-15 PSI _with_ the
pool cleaner attached. Does it? Or are you measuring the pressure
without the pool cleaner attached with the pump discharging some other
way? Are you measuring the pressure at the pump or at the cleaner?
Try attaching the cleaner and _then_ see what the PSI is at _both_
the pump and cleaner ends.

[I'm not familiar with the use of pool cleaners working on the
pressure side of the pump. It _may_ also be that your plumbing is
undersized or restricted. In which case, the PSI at the pump
end will be okay, but at the cleaner end it won't be.]

Think of it this way - a device like the pool cleaner needs to be
specified at a specific pressure AND flow rate. Eg: "to operate
properly, this device needs 1GPM or more at a pressure of 15PSI
or more".

Secondly, the plumbing between the two devices matter - it has
to be large enough to permit the GPMs that the cleaner needs
without excessive PSI loss.

Industrial equipment is rated/matched that way. So are, for example,
tools for use with air compressors (eg: "this tool consumes
x CFM at y PSI").

The PSI of the output of a pump varies inversely with the GPM
the outlet is permitting.

Pumps _tend_ to have a given "PSI vs GPM" curve given the
HP rating of the pump. In the middle "design range" (of GPMs),
it's pretty much determined by the HP of the pump.

It's not linear, but at least for the most part, two pumps with
the same HP rating _should_ push just about the same amount of GPMs
at the same PSI as each other.

So, if it's the right HP, it (probably) _should_ work.

But, without knowing the GPM requirements of the cleaner or the expected
GPM vs PSI curve of the pump, it's difficult to be absolutely certain
whether a given combination _should_ work or not, and the best bet is
probably to call the manufacturer[s] (cleaner manufacturer _first_),
explain your situation mentioning model numbers etc, and they should be
able to tell you whether the cleaner or the pump are working in spec or not.

The cleaner manufacturer is probably intimately familiar with the
behaviour of the cleaner with every pump on the market. If they
tell you "we have lots of cleaner customers using that pump
satisfactorily", you _know_ that something's wrong with one
(or both) of the devices. They may tell you that there's
something specifically "odd" about that pump that means it won't
work. Or they may tell you that the plumbing is too small.


The pump is sending water to the wall outlet and then the cleaner is
attached to the wall. The 14-15 PSI reading is from the wall outlet
without the cleaner attached. When I take the measurement from the end
of the hose that attaches to the cleaner it's at 11 PSI. The hose is a
5/8" hose and is about 22 feet long.

The pump is a Magnetek 1081 PB4 Booster Pump, 3/4 hp, 3450 rpm - part
#173840-20 but I can't find the specs for it online.

I also did as you suggested and called the manufacturer of the cleaner.
Their 3/4 hp pump is capable of 67-80 GPM but they couldn't help with
the specs for my Magnetek pump and didn't have any info stating that
this pump wouldn't work with their cleaner. I'm still looking for a
phone number for Magnetek. Their website refers people to AO Smith
(http://www.aosmithmotors.com/html/contactUs.html) so I wrote to them
because they don't have a published phone number.

Thank you.
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Default How much PSI can this pump produce?


"Stuart Benoff" wrote in message news:echv51
The pump is sending water to the wall outlet and then the cleaner is
attached to the wall. The 14-15 PSI reading is from the wall outlet
without the cleaner attached. When I take the measurement from the end
of the hose that attaches to the cleaner it's at 11 PSI. The hose is a
5/8" hose and is about 22 feet long.


All these measurments are going to vary with the water flow. You need
to measure with the cleaner attached and operating, with no leakage which
will lower the reading. Where the booster pump gets its water will affect
the reading. If it connects to the water return line to the pool, it will start
with low pressure. If it connects to the outlet of the pump, before the
filter, it will start with higher pressure and end up with a higher boosted
pressure.

Bob


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Default How much PSI can this pump produce?

According to Stuart Benoff :

The pump is sending water to the wall outlet and then the cleaner is
attached to the wall. The 14-15 PSI reading is from the wall outlet
without the cleaner attached.


Is the wall outlet free flowing or plugged?

When I take the measurement from the end
of the hose that attaches to the cleaner it's at 11 PSI.


Same question.

The hose is a 5/8" hose and is about 22 feet long.


I think you need to connect the cleaner to the line and then
measure pressure, at both ends. The drop from 14-15 to 11
seems a bit high, suggesting the hose is undersized.

5/8" garden hose? Use 3/4" high quality hose. Some 5/8"
hoses are quite flow restricted, especially those with cheap
end fittings. This could be your problem right there.

The pump is a Magnetek 1081 PB4 Booster Pump, 3/4 hp, 3450 rpm - part
#173840-20 but I can't find the specs for it online.


3/4HP Magneteks appears to be one of the pumps of choice for pool
cleaners according to the number of hits on Google. Eg: they're
bundled with Polaris and other units.

So it should be working with yours.

I also did as you suggested and called the manufacturer of the cleaner.
Their 3/4 hp pump is capable of 67-80 GPM


67-80GPM at 20PSI? Good grief, that's _high_ for a 3/4HP unit. I'd
expect a pump delivering that performance to be 2HP or more.

You simply _cannot_ push 67 GPM thru even 3/4" copper pipe with any
sort of efficiency, the friction losses are _enormous_[+]. 13 GPM is
more like an acceptable upper limit thru pipe that size. 1/2" pipe
is around 8 GPM max, and garden hose (smaller "real" diameter compared
to nominal inside diameter) will be less. Especially since
some cheap garden hose has very restrictive hose fittings. Watch
out for restrictive valves too (if there are any valves in the line).
Use full aperture ball or gate valves. Washer type stop valves
are quite flow restrictive.

Are you sure they didn't say 6.7-8.0 GPM? _That_ is reasonable,
and suggests that the hose (if you supplied it) is likely at fault.

[+] There is a "practical speed limit" for efficient pushing of
water through pipe, above it, the friction loss becomes ridiculously
high. With 3/4" copper/PVC, that "speed limit" is achieved at roughly
13-15GPM. Trying to exceed 13-15GPM in 3/4" pipe means that you have
to size the pump FAR larger than necessary (and thus waste a lot
of money) to get the device to work. If you don't size the pump
that large, the device simply doesn't get the water volume it needs.
--
Chris Lewis, Una confibula non set est
It's not just anyone who gets a Starship Cruiser class named after them.


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Default How much PSI can this pump produce?

Chris Lewis wrote:
According to Stuart Benoff :


The pump is sending water to the wall outlet and then the cleaner is
attached to the wall. The 14-15 PSI reading is from the wall outlet
without the cleaner attached.



Is the wall outlet free flowing or plugged?


Free flowing


When I take the measurement from the end
of the hose that attaches to the cleaner it's at 11 PSI.



Same question.


Free Flowing


The hose is a 5/8" hose and is about 22 feet long.



I think you need to connect the cleaner to the line and then
measure pressure, at both ends. The drop from 14-15 to 11
seems a bit high, suggesting the hose is undersized.

5/8" garden hose? Use 3/4" high quality hose. Some 5/8"
hoses are quite flow restricted, especially those with cheap
end fittings. This could be your problem right there.


This is a 5/8" rigid high pressure hose kit supplied by Hayward. It has
several joints to allow the cleaner to reach the corners of the pool
without getting tangled on it's own hose. It's part number is AX6000HA
(retail cost is about $180) so this is no garden hose!


The pump is a Magnetek 1081 PB4 Booster Pump, 3/4 hp, 3450 rpm - part
#173840-20 but I can't find the specs for it online.



3/4HP Magneteks appears to be one of the pumps of choice for pool
cleaners according to the number of hits on Google. Eg: they're
bundled with Polaris and other units.

So it should be working with yours.


Right. I am thinking there's a problem with the pump. I'll open it up
and check the impeller, etc. It is 6 or 7 years old so maybe it's time
to replace it?


I also did as you suggested and called the manufacturer of the cleaner.
Their 3/4 hp pump is capable of 67-80 GPM



67-80GPM at 20PSI? Good grief, that's _high_ for a 3/4HP unit. I'd
expect a pump delivering that performance to be 2HP or more.

You simply _cannot_ push 67 GPM thru even 3/4" copper pipe with any
sort of efficiency, the friction losses are _enormous_[+]. 13 GPM is
more like an acceptable upper limit thru pipe that size. 1/2" pipe
is around 8 GPM max, and garden hose (smaller "real" diameter compared
to nominal inside diameter) will be less. Especially since
some cheap garden hose has very restrictive hose fittings. Watch
out for restrictive valves too (if there are any valves in the line).
Use full aperture ball or gate valves. Washer type stop valves
are quite flow restrictive.

Are you sure they didn't say 6.7-8.0 GPM? _That_ is reasonable,
and suggests that the hose (if you supplied it) is likely at fault.


I thought he said 67 but we had a small language barrier so I suppose he
could have said 6 to 7 and not 67. Now that I think about it 67 gallons
of water is a lot to move in 1 minute.


[+] There is a "practical speed limit" for efficient pushing of
water through pipe, above it, the friction loss becomes ridiculously
high. With 3/4" copper/PVC, that "speed limit" is achieved at roughly
13-15GPM. Trying to exceed 13-15GPM in 3/4" pipe means that you have
to size the pump FAR larger than necessary (and thus waste a lot
of money) to get the device to work. If you don't size the pump
that large, the device simply doesn't get the water volume it needs.


Thank you for your help!
Stu
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Default How much PSI can this pump produce?

According to Stuart Benoff :

[his posting showed that it was the proper "lines" for the
application.]

Right. I am thinking there's a problem with the pump. I'll open it up
and check the impeller, etc. It is 6 or 7 years old so maybe it's time
to replace it?


Pumps tend either to work to full (or darn close to full) spec, or not
at all. Anything "intermediate" to that will probably not be something
that needs the pump to be replaced (eg: plugged impeller, other
obstructions), or be very obvious (eg: the pump motor/bearings are _very_
hot, major housing leakage etc.).

Depending on how the impeller is designed, it may be partially plugged.
Or perhaps badly chipped.

Our pool pump plugs up with debris from a certain plant that sheds
for a short period during the summer - this stuff is rather like
short pine needles, gets through all the screens, and promptly
plugs up the impeller. It's not an "open impeller" (one circular
plate with vanes), it's more like a water wheel with very small openings
(two plates with narrow curved water channels between them). Has to be
disassembled and cleaned out once or twice a year with pipe
cleaners - you know, the "fuzzy wire" kind ;-). Symptom is simply
poor flow.

[Seem to have bypassed _that_ problem this year.]

Given that pool water is usually relatively well screened before
it hits the pump, that type of impeller could be fairly normal
for pool boosters too.

I thought he said 67 but we had a small language barrier so I suppose he
could have said 6 to 7 and not 67. Now that I think about it 67 gallons
of water is a lot to move in 1 minute.


Yah.
--
Chris Lewis, Una confibula non set est
It's not just anyone who gets a Starship Cruiser class named after them.
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Default How much PSI can this pump produce?

Stuart Benoff writes:

Right. I am thinking there's a problem with the pump. I'll open it up
and check the impeller, etc.


Advice in this thread is confusing pool *circulation* pumps with pool
cleaner *booster* pumps. They are very different. The booster pump
characteristics, the lines and hoses, and other components are not
comparable to the usual guidelines for circulation pumps.

Why? The purpose of the booster pump is to create and transmit hydrodynamic
power to the cleaner for application in the turbine motor and the venturi
vacuum, not so much to move water volume which is adequately delivered as a
by-product of the power transfer. This power has to go thru a skinny hose
so as to maintain flexibility. So you want a pump that delivers low volume
at high pressure. It's the opposite for pool circulation pumps, where you
want high volume circulating and absolutely don't care about pressure for
pressure's sake. This is analogous to electrical power transmission and
why high-voltage lines are used for long distances.

I am not up to date on the exact specs, but I believe your 15 psi is way
too low. When my Polaris 180 comes off the hose and the loose hose flails
around the pool, the water coming out is like an 80 psi city water faucet.
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