Prohibited Action | |
Contaminate pump with explosive vapors, | Lower explosive threshold of gas mixtures |
powders, or reactive materials |
|
Remove, defeat, or override safety counter- | Overtemperature, overpressure, more |
measures such as pressure and thermal | combustible mixtures |
switches and valve sequencer interlocks |
|
Machine or weld without removing all oil | Source of ignition |
or solvent residue in pump |
|
Use unsuitable pumping fluid especially | Lower explosive threshold of gas mixture |
in large pumps |
|
Systems larger than 10 inches must be designed with pressure relief devices to provide safe pres- sure relief from internal explosions. Always recognize that safety devices can fail or malfunction; pro- vide redundant protection by installing devices having different failure modes, failure mechanisms, and failure causes. Be certain that exhaust duct materials are capable of withstanding the corrosivity, temperature, and pressure of exhausted products.
c.Pressure – 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. 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 pres- sure relief motion is limited to safe envelopes. Never permit the following:
Prohibited Action | Result |
Block inlet and vent of liquid nitrogen | LN2 trap and/or lines burst |
trap and lines |
|
Close isolation valves at inlet and discharge | Water turns to steam and bursts coils |
of main watercooling coils and pump is |
|
reheated |
|
Pressurize pump body | Body of pump bursts |
Hole through vacuum wall | Loss of structural integrity of wall |
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