Absolute pressure transmitter issues
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This post was last edited by zhoudingshengs on 2024-2-19 08:39. Everyone is welcome to engage in active discussions: 1. For a certain project, an absolute pressure transmitter is used as the instrument for measuring the pressure at the top of the vacuum tower, with a designed range of 0–100 kPa. This measurement reflects the vacuum level inside the tower. According to the production requirements of the process, the production efficiency is highest when the vacuum level displayed on the upper-level control system reaches or approaches 100%. If the range of the absolute pressure transmitter at the site is set to 0–100 kPa, and the range of this instrument within the control system is set to -100–0 kPa, then the range displayed on the host computer for this instrument will be set to -100%–0, with the absolute value taken. Is this setting correct?
It is best not to express pressure in percentages; the host computer can be set to 0–100 KPa(A), or it can also be set to -100 KPa–0 KPa. Since absolute pressure is being measured, it is recommended to set it to 0–100 KPa(A)
This post was last edited by Hongyou_mKKF5 on 2024-2-19 09:19. (The pressure measuring instrument at the top of the vacuum distillation tower uses an absolute pressure transmitter, with a designed range of 0–100 kPa.) Since it is an absolute pressure gauge, why is its designed range positive pressure? I don’t understand.
Relatively, *set it to the one that is commonly used
It depends on what you’re used to using in your workshop: if it’s absolute pressure, then 0~100 is suitable; for gauge pressure, -100~0 would be better. This approach results in lower costs associated with staff turnover, and it’s less likely to cause confusion. It’s not recommended to use absolute values for the host computer
This setting is reasonable. If the pressure is at 25% of the range, the current value is 8 mA; the field absolute pressure transmitter displays 25 kPa, while in the control system this value is converted to –75 kPa. The instrument shows 75% on the upper-level computer, and this setting is based on the requirements of the production process. When complete vacuum is achieved, it displays 00%, which meets the production needs.
Most operators were not familiar with gauge pressure, and it took a long time to explain it to them
For absolute pressure values, it is recommended not to consider any conversion; just use the value as is.