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Old January 8th, 2020, 04:10 PM   #1
paulB
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Leak test sensor recommendations

This is not exactly PLC question. But members here are exposed to variety of devices. Maybe someone use something similar. I am looking for high precision pressure transducer PSIG or PSIA for small pressure range. We need this sensor to perform following air leakage test:
"The container should be tested at 10kPa (1.5psig) pressure. The container shall be pressurized and allowed to stabilize for 30 minutes before starting test. The pressure shall show no more than 0.086kPa (0.0125psig) change in 15 minutes"

Thank you in advance for any recommendations.

PaulB
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Old January 8th, 2020, 05:00 PM   #2
Tom Jenkins
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I suggest you contact Omega Engineering and Dwyer. They have low range transmitters.

You might also consider using water for the pressure test. 1.5 psi is very low, but it is still not usual to use a compressible fluid for testing because of safety concerns with a failure.
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Old January 8th, 2020, 05:57 PM   #3
James Mcquade
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I did the programming for a leak tester several years ago.
Leak test require specific data in the equation.

we tested the seal on product cans for air leaks to keep moisture out of the can. I was very detailed and had exact measurements.

from your description, I get the following.
you want to test a container to see if it leaks.
how big is the container?
1.5 psi is a very low pressure to test at.
allowing the container to sit for 30 minutes before testing is unrealistic for a pressure loss of 0.0125psig

in order to confirm your test works, you MUST have a container or some method of testing for a failure. the sad thing that you will discover is that no one can produce a leak orifice accurate enough for your verification test that the system works. we purchased several hand adjustable leak orifices and the calibration lab spent about 20 minutes on each one certifying it. if you dropped it, get another one. i'm sorry, I cannot remember the brand name, but they were very accurate.

please describe your application and maybe I can give you some help.

james
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Old January 8th, 2020, 06:02 PM   #4
danw
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To see a 0.086 kPa drop in pressure from a 10.000 kPa vessel to no less than 9.914 kPa, you need an instrument with a lot of resolution: the ability to read to a hundredth of an inch of water column. (I have to convert to inches water column to get a 'feel' for the pressures involved).

That's the same as seeing a 0.35" w.c. drop from 40.19" w.c. to no less than 39.84" w.c..

An industrial grade differential pressure transmitter range 0-50.0" w.c. is capable of registering that degree of change. Most any nowadays would be capable of displaying values in the engineering units of choice, directly.

A water manometer could be probably be read to 0.01" (a hundreth of an inch) with considerations for parallax and meniscus.
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Old January 9th, 2020, 10:35 AM   #5
paulB
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The application is to automate testing of welding quality on metal containers. Currently it is manual operation. Container is filled with air, soap water applied from outside and watching for bubbles. The requirement:
"The container should be tested at 10kPa (1.5psig) pressure. The container shall be pressurized and allowed to stabilize for 30 minutes before starting test. The pressure shall show no more than 0.086kPa (0.0125psig) change in 15 minutes"
is from customer (government) specification.

PaulB
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Old January 9th, 2020, 05:41 PM   #6
Copyleft
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Usually i use in automobile industry sensors from Keyence:
https://www.keyence.com/products/pro...ressure/ap-40/
And Fukuda (DG960).
https://www.fukuda-jp.com/en/product/f15/

Check the Fukuda site, they have many calculators:
https://www.fukuda-jp.com/en/dl/calculate/

This site explain a lot too.
https://www.cosmo-k.co.jp/english/le...ak-inspection/

Valves i use from CKD, for vacuum test i use SMC.
From Keyence i use AP43 and AP44 head, I asked to Keyence guy come here and give sample model AP48, i wanna see how this fit.

Last edited by Copyleft; January 9th, 2020 at 05:51 PM.
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Old January 10th, 2020, 09:30 AM   #7
paulB
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Copyleft, thank you for the links. We will study these materials.

PaulB
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Old January 10th, 2020, 10:29 AM   #8
jstolaruk
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Being a pressure decay test, a change in temperature of the environment and/or air will have a big influence on the results. Temperature stability will be crucial. (I prefer mass flow testing).
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