Fluke 750PA8, 750PA9, 750PA6, 750PA7, 750PD27 Instruction Manual

Fluke 750P

Series Pressure

Modules

Precision pressure measurement for
75X and 720 series calibrators

The 750P Series Pressure Modules are the ideal pressure
modules to enable gage, differential and absolute pressure
measurement with Fluke 750 and 740 series DPCs and 725,
726 MPCs to measure pressure.

• 0.025 % reference uncertainty

• 6-month and 1-year specifications

• Temperature compensated 0 °C to 50 °C

• Digital communication to calibrators, no analog

losses or errors

• Broad selection of ranges

• Gage, differential, dual range, absolute and vacuum

measurement models

A complete family of pressure modules

A family of 48 pressure modules covers pressure
calibrations from 0 to 1 in H
to 690 bar).

Gage pressure modules have one pressure fitting
and measure the pressure with respect to atmospheric
pressure. Differential pressure modules have two pres­sure fittings and measure the difference between the
applied pressure on the high fitting versus the low
fitting. Each module is clearly labeled for range, over­pressure and media compatibility. All modules include
NPT, metric (BSP) and M20 adapters.

Quick and easy measurements

Fluke 750P Series Pressure Modules are easy to use.
To measure pressure, connect the pressure module to
a pressure source or hand pump and then connect the
pressure module cable to the calibrator. Apply pressure
from the pressure source and it is displayed digitally
on the calibrator. At the touch of a button, the pressure
may be displayed in up to 11 different engineering
units. When used with the 750 Series Documenting
Process Calibrators, pressure readings can be date/time
stamped and stored electronically for later retrieval.
This saves time, eliminates errors, and supports com­pliance with quality standards and regulations.

85

0 to 10000 psi (2.5 mBar

2

Technical Data

Pressure module performance
and technology

Fluke 750P Series pressure modules are highly
accurate, with specifications that apply from 0 °C to
50 °C (32 °F to 122 °F), a feature that sets them apart
from other pressure calibrators. Many ranges have
total uncertainties of 0.04
uncertainties of 0.01
table).

This performance is possible through the innova­tive application of mathematics and micro-processor
power. Fluke pressure modules have silicon piezo­resistor sensors which consist of a resistive bridge
fabricated in a silicon diaphragm. Pressure applied to
the diaphragm causes a change in the balance of the
bridge which is proportional to the applied pressure.
The bridge balance change is not linear and is very
sensitive to temperature. However, since these effects
are quite stable with time and with repetitive changes
of condition, the sensors are carefully characterized.

During manufacture, Fluke pressure module sensors
are characterized by reading temperature and pressure
at multiple points. A least-squares regression is used
to calculate the coefficients of a polynomial expression
for pressure. The coefficients, unique to that pressure
module, are stored in the module’s memory.

Each module has its own microprocessor, allowing
it to run the measurement circuitry and to commu­nicate digitally with a calibrator. When connected to
the calibrator, the modules coefficients are uploaded
from the pressure module to the calibrator. Then, as
pressure measurements are made, raw sensor values
for pressure and temperature are digitally loaded to
the calibrator, where the raw sensor values and coef­ficients are manipulated to derive and display the
pressure reading.

This innovative technique provides several benefits:

1. Digital communication eliminates errors due to poor

connections and electrical interference.

2. The modules are inherently temperature-

compensated from 0 °C to 50 °C (32 °F to 122 °F).

% of full scale and reference

% of full scale (see specification

3. The modules are fully interchangeable because
all measurements are completed in the pres­sure module itself and then communicated to the
calibrator in digitized form. Modules are calibrated
independently of the calibrator, and can be used
with any 740, 750 or compatible 720 or 710 series
calibrator. Each module has its own serial number
to maintain independent traceability.

Sensor protection in isolated modules

Many of these modules (see table) incorporate a stain­less steel diaphragm to isolate the sensor. With these
modules, any medium that is compatible with stainless
steel can be used on the high side of the module.

Rugged construction

A urethane overmolding protects against shock if a
module is accidentally dropped and also seals against
dirt, dust, and moisture. Pressure connections are

1

” NPT female connection. A ¼” NPT Male, ¼” BSP/

/

8

ISO and M20 male adapter are also provided with each
pressure module.

Convenient setup

A one-meter cable between the pressure module and
calibrator reduces the length of connecting tubing to
the pressure source. The remote pressure head also
provides an extra margin of safety and convenience
by removing the calibrator and operator from the
pressure source in the event or need for semi-remote
measurements.

2 Fluke Corporation Fluke 750P Series Pressure Modules