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Pressure Calibration APPLICATIONS AND SOLUTIONS Страница: 21

Fluke 753 [21/32] Tech tips

The pressure gauge should be mounted in the same ori-

entation (vertical or horizontal) as in the process.

The reference pressure gauge (2700G) should be mount-

ed vertically.

For hydraulic comparators prime the ﬂuid with the prim-

ing pump, to remove any bubbles.

Measurement points should be distributed uniformly over

the calibration range. Conveniently source pressure with

a manual pump up to 300 psi, after that use an external

pressure supply.

For gas comparators use the ﬁne needle valve or ﬁne

adjustment screw press to precisely meter the pressure.

With hydraulic models use the screw press to source and

ﬁne adjust the pressure.

The source pressure can be adjusted until the device

under test is reading a nominal pressure or until the

reference gauge reads the nominal pressure.

• The key to a good experience in using a

hand pump, either pneumatic or hydraulic, is

to test and debug your test setup in the shop

before going to the ﬁeld. Minimizing the

number of pressure connections minimizes

the probability for leaks. Mount the test

gauge carefully to the test pump in the shop.

• Be sure to consider the hoses that connect

from the hand pump to the device to be

tested. There are a variety of specialty “no

tools required” connectors to connect to

the test hose to make this easy. If these

connectors are not available be sure to have

a variety of adapters, wrenches and PFTE

sealing tape to be able to connect from the

test hose to the input port of the device for

testing. If using “push ﬁt” hoses it is likely

they will eventually leak. Each time - a push

ﬁt hose is connected, it leaves a mark on the

test hose and eventually does not seal well.

To eliminate the leak cut off the affected

portion of the test hose so there is a clean

surface to connect to. This process will need

to be repeated with use.

• When attempting to get maximum pressure

out of a pneumatic pump, adjust the ﬁne

adjust vernier all the way to down to the stop

so turning the vernier increases the pressure.

When approaching the target pressure use

the vernier to increase to your target pressure.

• When using hydraulic hand pumps

remember the thermodynamic effect. Once

any ﬂuid is compressed, the temperature

increases and the ﬂuid expands. This

becomes obvious when pumping to a target

pressure with a hydraulic pump. Once

the target pressure is met the ﬂuid has

expanded. As the ﬂuid cools and contracts

the pressure quickly bleeds down until

it reaches temperature equilibrium, this

can take 5 minutes or more. Once the

temperature stops changing, dial the desired

pressure back in with the vernier adjuster.

STEP

To perform the test:

Additional resources

For more in depth information about

this application check out these videos

and application notes from Fluke.

Check out the 700G videos.

700G Data Sheet.

Interpreting Speciﬁcations for Process Calibrators,

Application Note

TECH

TIPS

Fluke 753 [21/32] Tech tips

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