Copyright 2008 Baker Hughes Company.
44 | PACE5000/6000 Instruction Manual–English
Chapter 6. Reference
The compressed gas supply must not contain particulates and must be removed using a
particulate filter. Do not use a compressed gas supply containing corrosive material.
6.1.5 Systems without a Negative Supply
Without a negative supply (vacuum pump), release the positive pressure from the system to
atmosphere through the negative supply port.
The release from the negative port must be piped away to where the discharge causes no
disturbance or hazard. A diffuser may be fitted to the negative supply port to diffuse air flow.
The need for a Negative Supply (for Optimum Performance)
6.1.6 General
Supply pressures (at least 110% of range but less than the MWP) there must be a difference of
10% of full-scale between the supply pressure and the maximum output pressure. When
operating at positive or negative full-scale, there must be a pressure difference between supply
and output to cause a gas flow.
6.1.7 Operating Near Atmospheric Pressure or Below
Any controller operating near atmospheric pressure or below requires a vacuum pump or other
negative supply connected to the negative supply port for optimum performance. Without a
vacuum supply, as the output pressure approaches atmospheric pressure, the differential
pressure approaches zero resulting in a reduced flow to the output.
Reduced flow causes an increase in the time to control to atmosphere, especially with large user
volumes, and an increased overshoot at low pressures. Refer to
Figure 2-6, Figure 2-7 and
Figure 2-8.
6.1.8 Vacuum Pump
Each PACE Control Module has a vacuum sensor. Connect a vacuum pump to the -ve supply
port. The higher the flow rate of the vacuum pump the better the PACE control performance. Low
pressure ranges <
700 mbar require vacuum regulation or the use of the negative gauge
pressure generator IO-NEG-G-GEN-1 option.
A vacuum supply should be used for:
• Absolute ranges.
• Negative gauge ranges.
A vacuum supply improves:
• Time to reduce system pressure at pressures below 2 bar (30 psi), full-scale.
• Control stability near atmospheric pressure.
• Overshoot at low pressures.
• Performance at or near gauge zero.
6.2 Operational Requirements
6.2.1 Negative or Vacuum Supply
The negative supply for absolute control does not need to be regulated. Any variation between
this and absolute zero will affect instrument operation if controlling at low absolute pressures.
CAUTION A contaminated UUT must have additional in-line filters connected
between the output port and the UUT to prevent contamination of the instrument.
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