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1. Consider
all possible chemical reactions within your system. Make allowance for
abnormal chemical reactions, including those which could occur under fault
conditions.
2. Refer to material data sheets when you
assess the potential hazards associated with your process materials.
3. Use dilution techniques to minimize reactions
with oxidants and flammable materials.
4. Use manufacturers' recommendations for
type of lubricant in your pump when you pump oxidants and pyrophoric materials.
5. When you perform safety calculations,
ensure that the safe working pressure for all components in the system
are taken into account. Ensure that you also take account of abnormal
and fault conditions.
6. Ensure that you incorporate the correct
type of pressure relief devices and that they are suitably rated for your
application.
7. If you pump hazardous materials, you must
design the system to fail to a safe condition. -You must not allow the
maximum pressure of the system to exceed the maximum pressure rating of
any single part of the system.
8. Leak test systems and equipment before
use.
9. No part of the body should be exposed
to vacuum. The exposure of small areas of the body surface to the suction
of a pumping system can result in tissue damage.
10. Exhaust hazard - Any dangerous substances
that may be present in the system being evacuated may pass through the
system into the pump and be emitted at the exhaust. Suitable precautions
must be taken.
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Vacuum Pump/System Hazardous
Overpressure
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1. Hazardous pressures may be produced
if the exhaust from a mechanical pump is restricted or blocked, and care
should be taken at all times to prevent this.
2. Exhaust line manifold systems should be
designed to cope with the maximum exhaust load that can occur.
3. Hazardous pressures may be produced in
the system to be evacuated if the rotary pump is operated in the reverse
sense. When a rotary pump motor requires a three-phase electrical supply,
the outfit should be checked for correct rotation after main connection,
before being connected to the system to be evacuated.
1. PFPE fluids produce toxic breakdown
products when heated above 280 Deg. C. Their use in diffusion pumps is
not recommended.
2. Cleaning Hazard - Suitable precautions
should be taken to protect personnel engaged in cleaning vacuum systems
from the solvents being used and from the process debris in the pump.
The exact precautions to be taken will be dependent on the cleaning solvent
involved but particular attention should be paid to the danger of inhaling
solvent vapors.
3. Oil mist hazard - Rotary pumps are
oil sealed and discharge small quantities of oil mist when operating.
In poorly ventilated areas this can lead to unacceptable concentrations
of oil vapor. Oil vapor should be kept to a minimum. It is strongly recommended
that a suitable oil mist filter is fitted to the pump or, alternatively,
the exhaust should be piped away externally.
4. Mineral-oil-based products are only
slightly to moderately irritating to the skin and eyes. Prolonged exposure
of the skin to mineral oils may give rise to dermatitis.
5. Care should, however, be taken to
avoid inhalation of vapors or mists arising from undue heating or excessive
mist generation. In the case of fluorinated compounds (e.g. Fomblin) avoid
contact with excessive heat (~ 280 °C), e.g. lighted cigarettes, heater
elements, etc.
6. Fluid spillage should be absorbed
with sand, earth or mineral absorbent and disposed of in the proper manner.
In the event of large spillage, steps should be taken to prevent pollution
of drainage systems, rivers or waterways.
7. The operating temperature of most
vapor pump fluids is of the order or 195 to 220 °c. This constitutes a
safe operating condition in a vacuum environment. However, a hazardous
condition with some fluids may occur if the fluid is permitted to overheat
excessively by allowing it to operate at or near atmospheric pressure.
Under these conditions, the fluid temperature may approach the auto ignition
point (depending on the fluid, in the range from 300 to 600 °C).
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