SECTION II

OPERATION

During initial installation, the newly installed pump fluid may be subjected to a degassing process. This may result in foreline pressure fluctuations and "bursts". Such fluctuations are considered normal.

2-1 START-UP PROCEDURE

WARNING

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The following conditions increase the risk of explosion:

any air leaks into the system

roughing through a hot diffusion pump may cause some hot hydrocar- bon fluids to ignite or explode when exposed to air

air release or admitting air to a pump with a hot boiler, permit a strong oxidizer to contact the hot pump oil

high (above 1 micron (.133 Pa)) inlet pressure

insufficient (or low level of) pump fluid

operating pump without cooling water circulating to main water cooling coils

operating pump with water trapped in quick cool coil

foreign matter in the pumping fluid which changes its viscosity and obstructs flow passages

CAUTION

Do not turn on the heater without fluid in the pump. This may ruin the heaters and damage the pump.

Do not air-release the pump while the boiler is hot. Most diffusion pump fluids are heat-sensitive and will break down under these conditions.

Do not operate the pump without the foreline baffle. This may cause a greater than normal fluid loss.

Do not operate the pump for extended periods at an inlet pressure above 1 micron (.133 Pa). High pressure operation may cause exces- sive backstreaming.

Do not operate the pump heater unless the cooling water is circulat- ing. It will cause the pump and fluid to overheat.

a.Evacuate the diffusion pump by means of the mechanical roughing pump to a pressure level below 0.5 Torr (66.5 Pa). The diffusion pump will not function unless the discharge pressure is less than the tolerable forepressure (approximately 0.5 Torr (66.5 Pa)).

b.Turn on the cooling water supply to the pump body and check that adequate flow is provided by examining the amount of water discharged at the visual drain points.

c.Switch on the power to the diffusion pump heater.

2-1

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Bissell HS-20 instruction manual Operation, START-UP Procedure