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The AMBIENT run screen displays:

<nnnnnnn uuuu>:

Current numerical value and pressure

unit of atmospheric pressure.  Source of value can be internal
measurement, remote barometer, normal  or user depending
on current SETUP selection (see Section 3.11). The unit of
measure is determined by the UNIT function setting (see
Section 3.10.3).  ATM head is applied to internal or external
barometer reading to correct atmospheric pressure to the
PG9000 reference level (see Section 3.12.3).  Indicates

< ----

when information is unavailable or out of range. Indicates

<TIMEOUT>

if the current SETUP selection is a remote

barometer and PG9000 communication with the barometer
times out.

nnnnnnn uuuu nn.n°C

nn%RH n.nnnnnn/s2

<n.nn°C>:

Current ambient temperature. Source of value can be internal measurement, normal or user

depending on current SETUP selection. The unit of measure is degrees Centigrade

[ºC]

and cannot be

changed. Indicates

< ---- >

when information is unavailable or out of range.

<n.nnnnnnm/s2>:

Value of local acceleration due to gravity. Can be normal or user depending on current SETUP

selection. The unit of measure is meters per second squared (m/s2) and cannot be changed.

<nn%RH>:

Current ambient relative humidity. Can be internal measurement, normal or user depending on

current SETUP selection (see Section 3.11). The unit of measure is percent relative humidity (%RH) and
cannot be changed. Indicates

< -- >

if current SETUP selection is internal and current measurement is

unavailable or out of range.

Pressing

[ESC]

in the AMBIENT run screen returns operation to the MAIN run screen. All

function keys are active from the AMBIENT run screen and operation returns to that screen
when leaving functions that were accessed from it.

Note

•

The current selection in SETUP determines the source of the values used
by PG9000 for atmospheric pressure, ambient temperature and relative
humidity. If the SETUP setting is “user” or “normal”, the AMBIENT screen
displays the specified value, not the real-time measurement from PG9000’s
on-board sensors.

•

To change the ambient pressure units of measure, see Section 3.10.3.
When the current pressure unit of measure is an altitude unit, atmospheric
pressure in the AMBIENT run screen is expressed in kPa if the altitude unit
is meters (m) or psi if the altitude unit is feet (ft).

3.10.7 [HEAD]



PURPOSE

To make a fluid head pressure correction for the height difference between the PG9000 and
a DUT.



PRINCIPLE

Calculation of the fluid head requires determination of the difference in height between the
PG9000 reference level and the level of the DUT. The PG9000 reference level takes into
consideration the piston-cylinder natural reference level, geometry and position.

The natural reference level of a piston-cylinder is defined as the height at which changes in
fluid density have no effect on the defined pressure.  For a solid floating piston the natural
reference level is located at the bottom of the piston. For hollow pistons (i.e. model PC-
7100/7600-10) the geometry is irregular and the natural reference level is located above the
bottom of the piston.  In order to create a convenient, single location for reference level
determination the PG9000 defines the reference level as the location of solid pistons at mid
stroke.  The calculated

reference level offset

(a variable that is associated with the piston-

cylinder metrological data file) of hollow pistons normalizes the different natural reference
levels to the same height, for convenience – the position of a solid piston at mid stroke or
reference level (see Figure 20). In this way the DUT height does not need to be determined
for each piston-cylinder that is used.