Regarding single-flange capillary gauge pressure transmitters and ordinary pressure transmitters
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I would like to ask the experts here a question: what are the differences and things to keep in mind when installing and using an absolute pressure transmitter with a single-flange capillary tube, as compared to a regular pressure transmitter with a single-flange capillary tube? If the transmitter is installed below or above the flange level, do these two types of transmitters need to be repositioned? How should they be set up separately? Especially with the issue of absolute pressure; I’ve been struggling to figure it out lately. I hope everyone can provide detailed guidance.
Like ordinary transmitters, it is necessary to secure the capillary tube, and migration or zero adjustment must be performed. For gauge pressure meters, the zero point needs to be calibrated first after installation, followed by migration. For example, if the range of a pressure gauge is -100KPa to 0KPa, it is first necessary to change the range to 0KPa to 100KPa, then calibrate the zero point, and finally change the range back to -100KPa to 0KPa ； Another example: if the range is -50KPa to 30KPa, first change the range to 0KPa to 80KPa, then calibrate the zero point, and finally change the range back to -50KPa to 30KPa.
Can the same be done for gauge pressure transmitters? It seems not possible, right? How to zero the gauge pressure? It applies to gauge pressure; I’m not clear about absolute pressure.
The single-flange capillary gauge for absolute pressure just doesn’t work well. Could you give me some advice? This is the gauge that’s used in the device; sigh!
You can definitely give it a try to see if the gauge pressure transmitter with a single-flange capillary is affected by its installation location! You can first install the flange, and then place the transmitter gauge at positions above, at the same level as, and below the flange, to see if there are any changes in the gauge readings! I installed it myself; at that time the flange was positioned high while the transmitter’s gauge was located low. The gauge showed -25 KPa, whereas the DCS required a range of -100 KPa to 0 KPa. So the range was adjusted to -125 KPa to -25 KPa, and it worked properly. When exposed to air, the gauge displayed 100%, the pressure read 0 KPa, and the current was 20 mA! Another way to ensure that the transmitter functions properly is the method I mentioned earlier: first adjust the range, then calibrate the zero point, and finally reset the range to its original value. Either of these methods works; in both cases, a handheld operator is required! If you don’t believe it, give it a try and you’ll see if it works!
Bro Pig! Is this property of capillaries also unaffected by their installation location? For absolute pressure gauges
I did try it, and there was some change but not much, so I’m asking what the reason is. Also, can the absolute pressure take on a negative value? Absolute pressure is the zero absolute pressure; it cannot be transferred as you mentioned. You must be referring to it in relation to gauge pressure.
Thank you, Pig Brother, for the detailed explanation: lol:handshake
There is no absolute rule regarding the use of any gauge; the gauge itself has its own accuracy limits, and the installation environment can introduce errors. What matters most is whether it functions well. The air pressure changes every day, and the value shown by the absolute pressure gauge is simply not referenced to atmospheric pressure. Furthermore, in terms of usage, several factories require precision at the mbar level
Normal inversion and reverse inversion are definitely different; although the silicone oil is enclosed in a diaphragm box, there is still a difference in height at different positions