Answer Posted / carl_ellis

Something is wrong with the stated situation. The stated range is in -0.5 to 2.0 bara, where bar is bar absolute.

An absolute pressure references absolute zero (a hard vacuum).

No measurement can be made below zero bar absolute because it violates the laws of physics.

While a DP transmitter can not make a negative absolute measurement, it can make a negative differential measurement where the low side pressure is higher than the high side pressure.

The method of changing the differential range depends on the brand/model of the transmitter.
- zero and span adjusting pots
- zero and span push buttons
- local indicator/push buttons
- HART communicator/modem-software

The first two require an applied reference pressure for zero and span.

The 3rd and 4th options might have a choice of applied pressure or entering values for zero and span.

Some DP transmitters do not have the same accuracy in the negative range as they do in the positive range.

Carl Ellis
Measure First

while am calibrating Drager polytron 2IR flame gas detector occured non zero status.how can i get zero status?

2148

---

What is the exact differences between HART,FOUNDATION FIELDBUS,PROFIBUS?

3405

---

What are different types of control valves?

1524

---

i want to find out iffco get test paper

12993

---

I will attend an interview with GasGas company for a position of Instrument Technician ( Offshore )in next month can anyone tell me what questions they will ask. Thanks in advance.

2031

---

how can leve transmetter calibate in feild .and also put cv and flow plz .....

2180

---

what is sil (safety integrity level

2678

---

How can we use feedback signal frm rtd for monitoring and in dcs for controlling ,then which type of rtd is sutaible 2 , 3,4wire and why ?

1574

---

Positioner usage.

1879

---

What is instrumentation control?

1102

---

principle of dead weight tester ?

2004

---

Hook up resistance decade box to temp.transmitter.

2193

---

Q1]IF THE RANGE FOR FLOW IS -35 TO 125 WHAT WILL BE THE SPAN FOR ABSOLUTE AND FOR NORMAL? Q2]HOW TO CALIBRATE CAPILLARY TYPE LT? Q3]HOW MANY ERROR CALCULATIONS ARE THERE USED IN PROCESS INDUSTRIES? Q4]HOW TO CALIBRATE TEMPERATURE TRANSMITTER? Q5] HOW TO CALIBRATE LEVEL TROLL AND HOW TO CONNECT? Q6]PLEASE TELL ME THE BASIC FOR INSTRUMENTATION WHICH IS APPLIED FOR CALIBRATION AND FOR ALL? PLEASE MAIL THE ANSWER TO honest_yes@yahoo.in

1891

---

hiii.... can any one provide me previous years question paper of hindustan petroleum for instrumentation engineering???

1933

---

can we copy the software from a transmitter using hht(hart 275) ?

2016

---