Fluke 750P Specifications
TECHNICAL DATA
Fluke 750P Series
Pressure Modules
Precision pressure measurement for
750 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.
• Up to 0.01 % 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
• Eight (8) Intrinsically Safe models that are certified to:
- NEC-500: Class I Div 1, Groups A-D, Ga
- ATEX: II 1 G Ex ia IIC T4 Ga
- IECEx: Ex ia IIC T4 Ga
* All certifications: Ta = -10 °C to +50 °C
A complete family of pressure modules
A family of 50 pressure modules covers pressure
calibrations from 0 to 1 in H20 to 10000 psi (2.5 mbar 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 pressure range 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.
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 % of full
scale and reference uncertainties of 0.01 % of full
scale (see specification table).
This performance is possible through the
innovative application of mathematics and microprocessor power. Fluke pressure modules have
silicon piezo-resistor 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.
This innovative technique provides several
benefits:
1. Digital communication eliminates errors due to
poor connections and electrical interference.
2. The modules are inherently temperaturecompensated from 0 °C to 50 °C (32 °F to 122 °F).
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 ⅛” NPT female connection. A ¼” NPT
Male, ¼” BSP/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.
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.
2 Fluke Corporation Fluke 750P Series Pressure Modules
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