Initial Vacuum Test - Agilent Technologies HS-16 Instruction Manual

Initial Vacuum Test

Before charging the pump with fluid, carry out this initial
vacuum test to establish the tightness of the system and its
vacuum connections.
Pumps and their components are designed for vacuum
service; they are not designed to be pressurized which
could cause them to burst possibly expelling shrapnel at
lethal velocities. Serious accidents have been caused by
intentional pressurization of vacuum systems and their
components.
WARNINGS
❑
Never pressurize any part of a
vacuum system for test or any
other purpose.
❑
Always provide pressure relief
when designing diffusion pumps
into systems and ensure that
pressure relief motion is limited
to safe envelopes.
High Throughput Diffusion Pumps
36
To perform the initial vacuum test:
1. Confirm the vacuum ultimate pressure characteristics
of the fore pump. This should closely approximate
the value quoted in the manufacturer's data, if the
mechanical pump is correctly installed, adjusted, and
filled with clean fluid.
2. Measure pressure with a continuously indicating total
pressure gauge, such as a capacitance manometer, or
thermocouple gauge.
3. Connect the outlet (or foreline) of the diffusion pump
to the inlet of the fore pump using vacuum-tight
connections.
4. The procedure varies for valved and unvalved
systems.
❑
For valved system: Close the roughing valve
and main isolation valve ahead of the diffusion
pump.
❑
For unvalved systems: Include the entire work
chamber volume in the test.
5. Evacuate the system using only the fore pump. Let
the pump reach an ultimate pressure in the system.
This reading should approximate the value obtained
in step 2 above (usually 10 to 50 microns, 0.013
mbar to 0.067 mbar).
6. If the pump does not reach this level, examine the
system for leakage following standard procedures for
leak testing. These procedures depend on the type of
vacuum gauges and leak detection equipment
available.
NOTE
Consult with your Agilent
representative for information on
Agilent's extensive line of helium leak
detectors.