A20M-AF Reference Pressure Monitor with High Pressure Mounting System Operation and Maintenance Manual

RPM4/HPMS A70M/A20M-AF OPERATION AND MAINTENANCE MANUAL

3.3.2 [UNIT]

 PURPOSE

To select the unit of measure in which RPM4 displays pressure values.

To select the measurement mode (absolute, gauge), use [MODE] (see Section 3.3.3).

 PRINCIPLE

RPM4 allows the unit of measure in which pressure values are displayed to be changed.

RPM4 A70M/A20M-AF supports 13 standard pressure units of measure as well as user

defined units. To simplify operation, quick access to six units is made available under the

[UNIT] key. The [UNIT] key contents can be customized by the user to any configuration of

six units (see Section 3.5.6).

Internally, RPM4 always operates in Pascal (Pa), the SI unit of pressure. Values of pressure

are represented in other units by the application of conversion factors to convert from Pa (see

Section 7.1.1).

 OPERATION

To change the active pressure unit of measure for a

range, press [UNIT] from the MAIN RUN screen while

the range is active. The display is:

1psi 2MPa 3kPa

4bar

The cursor is on the number corresponding to the active pressure unit of measure for the active range.

To change the pressure unit of measure, select the desired unit. Making the selection returns

to the MAIN RUN screen with the selected unit active.

The pressure unit of measure selected is range specific. When in a given range, all functions

and settings are represented in the current measurement unit for that range. However, certain

internal and/or metrological functions (e.g., Q-RPT calibration coefficients) are always represented

in Pa regardless of the current range unit.

See Section 7.1.1 for tables of the conversion factors used by RPM4.

If the pressure unit selected is inWa (inches of water), the reference temperature for water

density must we specified in a separate menu (choices are 4ºC, 20ºC 60ºF). No reference

temperature selection is necessary for the unit mmWa as the only reference temperature

commonly used for mmWa is 4 ºC.

The choice of up to six units available under the UNIT function can be customized from a

wider selection by the user (see Section 3.5.6). The units available under the UNIT function can be

reset to default by reset (see Section 3.5.9.2).