Skip to Content

Register Login

Industry Online Support

Technical Forum

Navigation

how to measure more than 4bar with a 0..4bar absolute transmitter

Created by: ionut.b at: 3/22/2009 9:45 AM (7 Replies)

Rating (1)

Thanks 0

8 Entries

3/22/2009 9:45 AM	Rate (0)
ionut.b Bronze Member Joined: 1/17/2007 Last visit: 10/6/2020 Posts: 289 Rating: (3)	I have an SITRANS P serias absolute pressure transmitter with a scale of 0..4bar and 4..20mA output. 7MF1564-5BE00-1AA1 I wonder if I can measure with it more than 4 bar. I am using S7-200 with an analogue module scaled to 4-20mA. I have observed that i can go up to approx. 4.13 bar - moment when the AIW reaches 32760; from here up the reading is blocked to 4.13 bar. Is it possible to measure 5 bar with this sensor? (of course not to go over the max. permissible pressure wich for this sensor is 8 bar). I would probably need to rescale the analog input in my program. Unfortunately on the same module I have connected two of these sensors, both with 0...4bar range, but I need to measure 5 bars only with one of them. Thank you.

Suggestion To thank Quote Answer

3/22/2009 5:11 PM	Rate (1)
ARGThomassey Regular Member Joined: 3/29/2007 Last visit: 1/31/2022 Posts: 14 Rating: (2)	Hello ionut.b The sensor that chosen you to, cannot be changed in your range.The instrument, this preparation to measure from 0 to 4 Bar (abs), the value that you observe of 8Bar (Abs)it is of overpressure. This equipment resists up to 8 Bar (Abs)of overpressure, before breaking. From 4 to 8Bar (Abs)the instrument does not measure. This extra range is only for protecting the equipment of excesses of process pressure. The economic solution, is buy another sensor from 0 to 6 Bar (Abs)7MF1564-5BG00-1AA1, and re-scale the input of the PLC. With its maximum pressure to 5 Bar (Abs), one will visualize, with 17.3mA , in the current scale. This implies to lose resolution in the measurement, but you would want to measure from 0 to 5 Bar (Abs)with your value of current represented in a scale from 4 to 20 mA, you need to choose by SITRANS ZD or SITRANS P300. Attached the selection by Pia-Selector. It excuses if the description is in Spanish but I have the program in my native language. The links www.siemens.com/pia-selector Web pressure www.siemens.com/pressure The catalog link in PDF https://pia.khe.siemens.com/efiles/instrumentation/catalogs/fi01/fi01_en_unit/FI01_2009_en_kap02.pdf Santiago T. Attachment 7MF1564-5BG00-1AA1.pdf (361 Downloads)

Suggestion To thank Quote Answer

3/22/2009 6:51 PM	Rate (0)
ionut.b Bronze Member Joined: 1/17/2007 Last visit: 10/6/2020 Posts: 289 Rating: (3)	Thank you ARGThomassey for your quick reply. You are right about the overpressure limit. Of corse the solution for me is to have the correct sensor - indicated by you. I am only asking for a temporary solution, even with a loss of accuracy. I was thinking to somehow alter the total resistance in the current loop so that at 4.13 bars to get a value smaller than 32760, and do a rescale. I don't know if this is possible or if someoe else tryed. Thank you.

Suggestion To thank Quote Answer

3/22/2009 7:43 PM	Rate (0)
UMENCHO Diamond Member Joined: 3/21/2006 Last visit: 11/1/2024 Posts: 10229 Rating: (1181)	Hello Basicly you are right. In this way is possible to change the measure limits. But in practice, I don't think that this would be works, that this would be possible to be prepare with necessary accuracy. My suggestion is to keep old limit and in software to prepare some magic. (If you want only to detect this pressure, not to control valves ) regards

Suggestion To thank Quote Answer

3/23/2009 10:58 AM	Rate (0)
ionut.b Bronze Member Joined: 1/17/2007 Last visit: 10/6/2020 Posts: 289 Rating: (3)	Thank you Umencho. I will do the magic.

Suggestion To thank Quote Answer

3/26/2009 11:10 PM	Rate (0)
ionut.b Bronze Member Joined: 1/17/2007 Last visit: 10/6/2020 Posts: 289 Rating: (3)	My new sensors with 0..6 bar abs arrived, so my problem with measuring a higher pressure is solved. I have one observation to make. If I open the sensor at the back (remove the DIN plug and unscrew the big plastic nut)there are two small potentiometres. According to the leaflet included in the box, one is for zero, marked with letter "Z" and one is for scale, marked with letter "S". I will try toincrease the measuring range with the help with the scale potentiometer.

Suggestion To thank Quote Answer

4/6/2009 6:58 AM	Rate (0)
ARGThomassey Regular Member Joined: 3/29/2007 Last visit: 1/31/2022 Posts: 14 Rating: (2)	Hi, ionut.b It´s the good news, that it finds arrived your sensor. The potentiometers that you mention. They´re for calibrating the equipment, Zero error of drif and Spanajustscale bottom. But I don´t believe, that´s sufficient to change the range, of the equipment. Successes Best regards Santiago

Suggestion To thank Quote Answer

4/8/2009 2:47 PM	Rate (0)
alindsay Posts: 45 Rating: (0)	some pressure transmitters allow you to adjust the scale by upto 25%, on a 4 bar tx this would give 5 bar Andy.
alindsay Posts: 45 Rating: (0)
Suggestion To thank Quote Answer

|

Share this page:

Share this page on...

Follow us on