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There are total 12 models
available for our pressure switches. The selection of a model is based
on main two criteria like...........(01) Pressure control requirement
and (02) requirement of facilities like valve & on-off knob
switch. We discuss both the criteria hereunder........:-
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(01) Selection on
the basis of pressure control requirement.
Basically, there are three available ranges 4,9 & 15
of pressure as given below.....
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| Sr. No. |
PRESSURE
RANGE |
MODELS |
CUT OUT
PRESSURE RANGE |
| 01 |
4 |
PR-4, PR-4X, PRV-4X, PRV- 4 |
1 to 4 kg/cm2
(14 to 58 PSI) |
| 02 |
9 |
PR-9, PR-9X, PRV-9X, PRV -9 |
2.5 to
9.5 kg/cm2 (35 to 135 PSI) |
| 03 |
15 |
PR-15, PR-15X, PRV-15X, PRV-
15 |
7 to
15 kg/cm2
(100 to 213 PSI) |
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What is the cut out
pressure
:-
Cut-out pressure (or stopping
pressure) is the pressure set at which the motor stops.
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What is the
differntial
:-
The differential is the difference of pressure between the stopping & starting pressure.
Once the motor is stopped, some amount of pressure must be allowed to
reduce before the motor can be restarted. This is known as the
differential. It is adjustable within the given limit. (Click
ordering & Technical data at the end of this page for details.) |
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So, based on the
requirement of pressure range, a model can be selected from the
available range of model
4, 9 or 15. |
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(02) Selection on
the basis of facilities.
There are models available with or without unloading valves & with
or without on-off knob switch as mentioned below........ |
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| MODELS |
FACILITIES |
| PR-4, PR-9,
PR-15 |
Without unloader
& knob Switch |
| PR-4X, PR-9X,
PR-15X |
With knob Switch
BUT without unloader |
| PRV-4X, PRV-9X,
PRV-15X |
With unloader
& knob Switch |
| PRV-4, PRV-9,
PRV-15 |
With Unloader
BUT without knob switch |
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The use of the
unloader valve :-
The unloader valve relieves the pressure trapped between the
compressor piston top & the N.R. valve when the compressor motor
stops. So, when the motor restarts, there is no starting load, thereby,
increasing the motor life.
The unloader valve relieves the pressure trapped between the
compressor piston top & the N.R. valve when the compressor motor
stops. So, when the motor restarts, there is no starting load, thereby,
increasing the motor and compressor life. |
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The use of on-off
knob switch :-
The use of the knob switch is to stop the
compressor motor by manually turning it off in clockwise direction
before the stopping pressure is reached. To restart, the knob must be
turned anti clockwise. So, the use of the knob switch enables manual local
on-off of the compressor motor without having to reach the main starter
(before the stopping pressure is reached.)
However, if the motor is stopped manually within the differential
pressure range, pressure must be allowed to reduce below the
starting pressure set to enable the motor to be restarted
manually. |
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