Anyone got a quick on-line source for some pressure transducers? I need
a ballpark number for a grant proposal ASAP. These would go on the high
and low sides of a standard R134 refrigeration setup. low side would be
soft vac to perhaps 25 or 50 psi, high side would be 0 to 250 psi. These
are lab demos, would not need to be super accurate but would need to
clearly distinguish 1/4 to 1/2 psi. Output would be something analog,
open to suggestions. It would be used in conjunction with a thermocouple
input box so I would need to do some signal translation somewhere.

And no, I did not google, the stupid tractor is sick, trying to do two
things at once.

On May 10, 2:25*pm, RoyJ wrote:
Anyone got a quick on-line source for some pressure transducers? I need
a ballpark number for a grant proposal ASAP. These would go on the high
and low sides of a standard R134 refrigeration setup. low side would be
soft vac to perhaps 25 or 50 psi, high side would be 0 to 250 psi. These
are lab demos, would not need to be super accurate but would need to
clearly distinguish 1/4 to 1/2 psi. Output would be something analog,
open to suggestions. It would be used in conjunction with a thermocouple
input box so I would need to do some signal translation somewhere.

And no, I did not google, the stupid tractor is sick, trying to do two
things at once.

Look here- http://www.omega.com/pressure/psc.html
I buy pressure transducers from them often

On Sun, 10 May 2009 14:25:23 -0500, RoyJ
wrote:

Anyone got a quick on-line source for some pressure transducers? I need
a ballpark number for a grant proposal ASAP. These would go on the high
and low sides of a standard R134 refrigeration setup. low side would be
soft vac to perhaps 25 or 50 psi, high side would be 0 to 250 psi. These
are lab demos, would not need to be super accurate but would need to
clearly distinguish 1/4 to 1/2 psi. Output would be something analog,
open to suggestions. It would be used in conjunction with a thermocouple
input box so I would need to do some signal translation somewhere.

And no, I did not google, the stupid tractor is sick, trying to do two
things at once.

DigiKey has a wide selection.
www.digikey.com

You may need to cook up (or include cost of) some interface
electronics for some of them, others may have standard 4-20ma or 0-5
volt interfaces.

RoyJ wrote:
Anyone got a quick on-line source for some pressure transducers? I need
a ballpark number for a grant proposal ASAP. These would go on the high
and low sides of a standard R134 refrigeration setup. low side would be
soft vac to perhaps 25 or 50 psi, high side would be 0 to 250 psi. These
are lab demos, would not need to be super accurate but would need to
clearly distinguish 1/4 to 1/2 psi. Output would be something analog,
open to suggestions. It would be used in conjunction with a thermocouple
input box so I would need to do some signal translation somewhere.

And no, I did not google, the stupid tractor is sick, trying to do two
things at once.

http://web1.automationdirect.com/adc...e_Transmitters

You will need to order an M12 size cable for them also , such as this one:

http://web1.automationdirect.com/adc...D12M-0B-070-C1

They have vacuum transducers, and pressure transducers, but I don't see
any of them that cover vacuum and pressure both.

Those seem to be about what I was expecting (hoping??) to find. $125
each plus $10 to $15 for the cable, 0-10volt output. I need two per
system, 5 systems to modify.

Don mentioned Digikey. While they may have what I need, they have 758
pages (no lie, that's what the search engine said!!) that I would need
to sort through. The cheap ones that run about $50 are not refrigeration
grade connections.

Gerry mentioned Omega. Nice stuff, pretty pricey.

Thanks for the responses, now to put it together for the grant.

PS. The new (old) engine is installed on the tractor, rebuilt the carb,
cleaned the gas tank (I've NEVER seen one that gummy!!!), and got the
PTO clutch working. The grass is growing, I was going to be pushing a
hand mower pretty quick.

JohnB wrote:
RoyJ wrote:
Anyone got a quick on-line source for some pressure transducers? I
need a ballpark number for a grant proposal ASAP. These would go on
the high and low sides of a standard R134 refrigeration setup. low
side would be soft vac to perhaps 25 or 50 psi, high side would be 0
to 250 psi. These are lab demos, would not need to be super accurate
but would need to clearly distinguish 1/4 to 1/2 psi. Output would be
something analog, open to suggestions. It would be used in conjunction
with a thermocouple input box so I would need to do some signal
translation somewhere.

And no, I did not google, the stupid tractor is sick, trying to do two
things at once.

http://web1.automationdirect.com/adc...e_Transmitters


You will need to order an M12 size cable for them also , such as this one:

http://web1.automationdirect.com/adc...D12M-0B-070-C1


They have vacuum transducers, and pressure transducers, but I don't see
any of them that cover vacuum and pressure both.

On Sun, 10 May 2009 18:33:39 -0500, JohnB wrote:

They have vacuum transducers, and pressure transducers, but I don't see
any of them that cover vacuum and pressure both.

Psst! PSIA (for Absolute) *is* vacuum - true 0 PSIA is a total
vacuum. 14.7 PSIA is 0 PSIG (Gauge), AKA atmospheric pressure at sea
level...

These sensors might not be accurate enough at the bottom of their
range to determine refrigeration system evacuation levels down in the
micron range. You need a different sensor for that.

-- Bruce --

The application is for a running system. On a freezer system, the low
side gets fairly low pressure but nothing close to hard vac.

Bruce L. Bergman wrote:
On Sun, 10 May 2009 18:33:39 -0500, JohnB wrote:

They have vacuum transducers, and pressure transducers, but I don't see
any of them that cover vacuum and pressure both.

Psst! PSIA (for Absolute) *is* vacuum - true 0 PSIA is a total
vacuum. 14.7 PSIA is 0 PSIG (Gauge), AKA atmospheric pressure at sea
level...

These sensors might not be accurate enough at the bottom of their
range to determine refrigeration system evacuation levels down in the
micron range. You need a different sensor for that.

-- Bruce --

On Sun, 10 May 2009 14:25:23 -0500, RoyJ
wrote:

Anyone got a quick on-line source for some pressure transducers? I need
a ballpark number for a grant proposal ASAP. These would go on the high
and low sides of a standard R134 refrigeration setup. low side would be
soft vac to perhaps 25 or 50 psi, high side would be 0 to 250 psi. These
are lab demos, would not need to be super accurate but would need to
clearly distinguish 1/4 to 1/2 psi. Output would be something analog,
open to suggestions. It would be used in conjunction with a thermocouple
input box so I would need to do some signal translation somewhere.

And no, I did not google, the stupid tractor is sick, trying to do two
things at once.


Check Setra.