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Understanding the 9013 pressure switch and how
to set it is a fairly easy operation.
If you remove the cover, you'll see a label on the inside.
The inside label will list the pressure setting that this device was
set to from the factory.
The switch itself will have two springs if it
has an adjustable differential or only one spring
if the differential is not adjustable.
The larger of the springs sets the range.
The smaller of the springs sets the difference
between the On and Off points.
The large spring adjusts the range of the entire device,
moving both the On and Off points by the same amount as the spring is tensioned.
Three turns of the nut adjusts the tension by 10 PSI.
If you tighten the nut three complete turns,
you've increased the pressure by 10 pounds.
A 20-40 switch then becomes a 30-50.
If you loosen the nut three turns, it lowers it 10 pounds.
A 30-50 switch adjusted 10 pounds lower becomes a 20-40.
You'll note that the only difference in the switches themselves
is the adjustment tension on the spring, which is identified in the part number
by a J code.
Different J codes for the same device use the same base switch
and only adjust the tensions.
We use J codes to identify the different pressure ranges of the switches
that we manufacture so that when we ship them,
we can easily identify their set points.
For instance, we have a 30-50, which is a J21.
If, however, we have a switch with a single adjustment,
a non-adjustable differential, we only have one pressure setting,
for instance, often 100, which identifies
a non-adjustable differential.
The other issue we have is in a reverse action device where
the pressures are actually in reverse.
In other words, the turn-on point is higher than the turn-off point.
And the J code must reflect that.
A 22-16 pressure switch turns on at 22, off at 16.
You cannot say 16-22 and get the same thing.
That would turn on at 16 and turn off at 22,
which is a different type of device.
The 9013 pressure switch comes either with an adjustable differential,
or a non-adjustable differential.
Most water switches that people are familiar with have two
springs, both of which are adjustable.
One adjusts the differential, the difference between on and off.
The other sets the range of the device and identifies where
both the on and off points are located.
Switches used for pressure control of an air compressor,
however, have the two springs, but the smaller of those springs
is a non-adjustable differential and is tensioned at the factory
and locked to set the differential at a fixed value.
It should not and cannot be adjusted.
The larger spring is the adjustment that moves the off pressure either up
or down, depending on the tension of the spring.
Turning the nut on the larger spring three complete turns
will adjust the pressure by 10 pounds.
Tightening will increase the pressure.
Loosening will decrease the pressure.
The differential will remain fixed at whatever value that particular device
was manufactured to.
If it was 20 pounds, it remains 20.
If it was 30, it remains 30.
OEM devices that are commonly used in large volumes for water systems
will only have one spring.
This is not an anomaly, but rather is a way
for a manufacturer to set their water supply
system with a simple single adjustment.
This device, should it ever need replacement,
can be replaced with a device with adjustable differential.
The adjustable differential can be set to match the original switch
manufactured for the system.