Water Pressure Sensor transmitter installation

[azka]

Hi expert forumer,

I need advice to install water pressure transmitter at Chiller water pipe, I have two option to install whether to use copper tube or not. Please refer to image attachment for more info. I don't know which is good for installation. What the advantage using copper tube.

thank you for advice.

[desert guy]

The drawing to the left shows a "pigtail" which is used to isolate the sensor from the pipe when used to monitor the pressure of Steam. It is commonly refered to as a "Steam Pig Tail". You don't need it for Chilled Water.

[azka]

The drawing to the left shows a "pigtail" which is used to isolate the sensor from the pipe when used to monitor the pressure of Steam. It is commonly refered to as a "Steam Pig Tail". You don't need it for Chilled Water.

Is it without "pigtail" will be effect for the water pressure reading? For information, this water pressure is to control VSD pump.

[Nuclrchiller]

Desert guy, is the pigtail used to isolate the sensor from the high temperature of the steam pipe, to avoid heat damaging the sensor? Azka, desert guy is correct that you do not need it for chilled water, however, I would prefer it if it were my system. That is because of the potential for water damage to the sensor due to condensation on the sensor, since it will be at pipe (or chilled water) temperature. Using the "pigtail" will keep the pressure sensor's temperature closer to ambient and should greatly decrease the chances of condensation. The slightly higher cost of installation will be more than offset by longer life and reliability of the sensor. Not to mention downtime, or system malfunction, due to a failed sensor.

[desert guy]

Here is some info that may be helpful. http://www.kele.com/pressure/47b,-47...-747s,-pt.aspx

While a single pressure sensor can be used as a reference to control the speed of a pump the more common approach is to use a differential pressure transmitter between the CHWS and CHWR pipe. This is usually placed at the furthest branch of the piping run before the last AHU. For reference I'll show the following transmitter. http://www.veris.com/Item/PW2LX04S.aspx

[azka]

Here is some info that may be helpful. http://www.kele.com/pressure/47b,-47...-747s,-pt.aspx

While a single pressure sensor can be used as a reference to control the speed of a pump the more common approach is to use a differential pressure transmitter between the CHWS and CHWR pipe. This is usually placed at the furthest branch of the piping run before the last AHU. For reference I'll show the following transmitter. http://www.veris.com/Item/PW2LX04S.aspx

Thank you for the link and info.

Desert guy, is the pigtail used to isolate the sensor from the high temperature of the steam pipe, to avoid heat damaging the sensor? Azka, desert guy is correct that you do not need it for chilled water, however, I would prefer it if it were my system. That is because of the potential for water damage to the sensor due to condensation on the sensor, since it will be at pipe (or chilled water) temperature. Using the "pigtail" will keep the pressure sensor's temperature closer to ambient and should greatly decrease the chances of condensation. The slightly higher cost of installation will be more than offset by longer life and reliability of the sensor. Not to mention downtime, or system malfunction, due to a failed sensor.

Dear Nuclrchiller,

I'm also afraid without "pigtail" will be damaged the sensor. This sensor will be use for control VSD pump. Maybe the best choice is to use "pigtail". Most of the pressure transmitter very costly.

[desert guy]

The pigtail is not required or necessary and there will not be any damage to the sensor if it is not used. For the sensor to function correctly it must be in contact with the liquid, in your case Chilled Water.
The sensor is designed to be immersed in the water.

[Nuclrchiller]

I really can't tell from here, looking at a hand-made drawing on my monitor, if that sensor has exposed wiring connections, or is made of a material that could be damaged by condensation causing an electrical short, or rust. And I'm also not able to tell if that pressure sensor is designed to be immersed in water. But if a pigtail, or anything similar is used, you (Azka) should be aware that the sensor needs to be kept at the height as the connection point on the pipe. I am also wondering what is the purpose of the sensor. As Desert Guy mentioned, a differential pressure sensor is usually used to control a VSD pump.

[WillyTech]

You do not need a pigtail or the copper tubing most pressure transducers come male pt. In this case the trouble of remote mounting your transducer running copper tubbing is not worth the time or cost.

[azka]

Hi guy, I'm using this type of sensor http://www.dwyer-inst.com/Product/Pr.../Series626-628
Before this I'm never use "pigtail". But some site that use this sensor got faulty. I don't know why this sensor faulty. Maybe due to condensation or high pressure water. All wiring is correct. That why I'm thinking to use "pigtail".

[WillyTech]

A pigtail is only used in steam application to protect the gauge from heat caused by direct steam. There is a plug of water in the "trap" that keeps the steam from reaching the gauge.

[WillyTech]

I use Setra model 206 for 4-20 applications.

[desert guy]

Hi guy, I'm using this type of sensor http://www.dwyer-inst.com/Product/Pr.../Series626-628
Before this I'm never use "pigtail". But some site that use this sensor got faulty. I don't know why this sensor faulty. Maybe due to condensation or high pressure water. All wiring is correct. That why I'm thinking to use "pigtail".

The sensor electronics are sealed so condensation should not effect the sensor. Once the operating pressure of the system is established by the Water Balance Contractor it should not deviate very much. What is the range of the sensor you are using and what is the maximun system pressure.
When I looked at the Catalogue Sheet for the sensor the Max Pressure was 2.5 to 3 times the pressure range so I don't think that the sensor failures are attributed to pressure or condensation.
How much pressure is indicated on the gauge at the discharge of the pump?