how to calibrate temprature switch and flow switch ?
Answer / carl_ellis
The key to 'calibrating' a temperature switch is it is a
switch, it is not a continuous analog sensor. So there's
no need to mess around with a zero and span value, like you
would on temperature transmitter.
All that matters is setting the switch's trip point, the
setpoint, and in some cases, the reset
(deadband/hysteresis) point. There is no need to mess
around anything but the trip point, it's time consuming
enough to get a precise setpoint on switch.
You need to know
- the setpoint
- in some cases, the reset (deadband/hysteresis) point
values
- whether the setpoint (SP) is for a rising or falling
temperature. Because they're mechanical switches, a SP for
falling is NOT same as a SP for rising.
- switch functionality - Does the switch close or open on
rise or fall. There are applications for all the
variations: close on rise, close on fall, open on rise,
open on fall.
Check how to change the setpoint on the switch. Some
switches have a setpoint lock (nut). Some are blind
adjustments, some are adjustments with indicated
temperature values. Some have a separate
deadband/hysteresis adjustment. The latest temperature
switches are digital, and the setpoint and hysteresis reset
point are entered as values.
Many procedures require an actual test with a calibrating
heat/cold (dry block calibrator or oil bath) source and a
temperature "standard" is needed for a reference
temperature, to prove the mechanical setting is correct.
Sometimes the standard is a certified dry block with a
readout, sometimes it's a mercury thermometer, sometimes
its certified RTD with a certified readout. Older cal
equipment has stand-alone electrical equipment, like an
indicator lamp or an ohmmeter that is used to indicate
switch closure on the temp switch, more modern cal
equipment has built-in connections and an indicator for
that.
Make the setpoint adjustment, run the temperature source,
heat or cool, and note the trip and reset points. If
needed, make adjustments and re-run the test until the
setpoint (and reset point) are within the spec needed.
Record the results, put a cal sticker or tag on the beast,
and you're on to the next one.
Tell 'em Carl sent you.
Is This Answer Correct ? | 8 Yes | 1 No |
Explain what is meant by the term “FLASH POINT” of liquid?
What are the reliability data ,like failure rate etc,for bently nevada systems & vibration probes.
How INtools is useful for routine Instrument maintenance?
What kind of feedback is used in DP cells.
If P will increase then what will happen with PID?
1 Answers Chettinad, Galfar, Mehran Sugar Mills,
Level in tank under vacuum (Ex: Condensate Tank of Power Plant)is measured using D. P. type level transmitter. Tank is subjected to vacuum of 755mmHg. Is it possible to fill wet leg ( i.e. leg connected to top of vessel with low point of D. P. xmtr) with water?. Are there chances of water getting sucked under vacuum? if yes, what is the solution?
how to calibrate temprature switch and flow switch ?
in sulfur process what is material of impulse line we use to connect with transmitter ? and does teflon affected by sulfur?
what is the difference between RS 232,RS 485,RS 422, how they different from each other
What is the difference between pt100, pt500 and pt1000 RTDs?
I have transmitter of range -20 to -5 kpa.if it is possible to zero trim with atmospheric pressure,means HP and lp having no pressure...what will get after zero trim and it is the right way.....plz give me reply ....
how the 4 to 20 mA signal goes to any controller/indicator,and what is the role of voltage ,12/24 and how to do connection of it, in controller.