Ans: a) Manometers (For low Pressure Inst)
b) Pneumatic Calibrators (e.g
Wallace & Tiernan)
c)
Dead Weight Testers
d)
Hand Pumps with Standard Pressure Gauge
Q2: Describe step by step how you
will assemble the parts of Control Valve?
Ans: a)
Carefully fix the Seat, Cage and Plug in the Valve Body
b) Put required gaskets and fix the
Bonnet tightly
c) Fill the gland packing, use grease
for lubrication and fix gland plate
d) Fix the actuator and couple the
stem with actuator (make sure valve is full closed and proper spring tension is
adjusted)
e) Fix feedback links, Valve
positioner and Air regulator.
f) Stroke check the valve and make
adjustment for final calibration
g) Leak test the valve in full close
position.
Q3: Explain how the Float Level
Switch works?
Ans: Liquid Fills in to the Level Switch Chamber, Which
makes the float to move, the Float is linked with Iron core which moves in the
head assembly inside the tube and magnetic module with micro switch assembly is
fixed externally on the tube gets actuated as the Iron cores moves in and comes
closer to magnetic module. The micro switch contacts get changed and gives
signal to control room.
Q4: What are the advantages
of Valve Positioner?
Ans: a) Split
range calibration.
b) Boosting up output signal for quick action.
c) Precise
control due to feedback signal.
d) Reversing
Action of Control Valves.
Q5: What are the common
parts in pressure gauge.
Ans: a) Bourdon Tube, Linkage, Sector and Pinion, Pointer
and Dial.
Q6: What is Span mean of
the instrument mean?
Ans: It is the valve of the range of the instrument. E.g
if the range of instrument is 50~200 deg C than the span is 150 deg C. So max
range – min range = span.
Q7: What is function of Air
Filter Regulators used on all pneumatic instruments?
Ans: As the name itself says, It filters out the small
particles in the air and restricts moisture from reaching the instruments. The
instruments need certain amount of pressure to function and that required
pressure is adjusted by the regulator.
Q8: What is meant by I/P
converter. Explain briefly where and why it is used?
Ans: It is basically a transducer which converts one form
of signal into another form I/P converts current signal 4~20 milli amp. To
pneumatic signal 3~15 psi. It is widely used on the control signal the valves
positioners, since we receive signal from control room is electrical signal
(Current ‘I’) we need to convert that signal into air pressure (P) as the
control valves are operated on pneumatic system.
Q9: Name commonly used
Temperature Measuring Elements?
Ans: 1) Bimetallic Strips used in Dial thermometers
2) Filled
Thermal System - Capillary type Temp. Sensors
3)
Thermocouples
4)
Resistance Temperature Detectors (RTD’s)
5)
Thermistors
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