Flowserve High Temperature Metal Bellows Seals - Manual (Page 6)

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absorbed by the gaskets. Any remaining water may vaporize when exposed to
high product temperatures and damage gaskets. Rebuilding flexible graphite
gasketed seals after water testing is recommended to prevent this issue.
5 Operational Recommendations
5.1 The shaft speed and pressure and temperature in the seal chamber must
not exceed the maximum seal limits.
5.2 For seals using external cooling or flush, these fluids must be supplied
before startup and before product is introduced to the pump.
5.3 Avoid unnecessary valves in any seal support system. Critical fluid flow
will be stopped if these valves are inadvertently closed.
5.4 Single and dual non-pressurized (tandem) seals require adequate vapor
pressure margin in the seal chamber to prevent flashing of the product at
the seal faces.
5.5 Dual non-pressurized (tandem) seals require buffer fluid pressure below
seal chamber pressure at all times.
5.6 Dual pressurized (double) seals require barrier fluid pressure at least 2
bar (30 psi) above seal chamber pressure at all times. It is imperative to
pressurize the barrier fluid before pressurizing the equipment to prevent
product intrusion into the barrier system. Likewise, pressure must be
maintained on the barrier fluid until the equipment has been fully isolated,
depressurized and vented.
5.7 Ensure that the barrier/buffer fluid is clean and compatible with the prod-
uct. The buffer/barrier fluid must contain little or no additives for anti-wear/
oxidation. Automotive antifreeze should never be used. Flowserve can
provide information on barrier/buffer temperatures and flow requirements
based on product type, seal size, product temperature, barrier/buffer fluid
characteristics and shaft speed. Dual gas seals should use clean steam at
all times.
5.8 This seal is designed to resist corrosion by the product(s) listed on the
assembly drawing. Do not expose the seal materials to products other
than those shown on the assembly drawing. The seal assembly drawing
lists the materials of construction. Consult your Flowserve representative
when in doubt or when using the seal for another application than
for which it was selected.
5.9 Liquid seal requirements:
5.9.1 Do not start the equipment dry.
5.9.2 Vent all air and/or product vapor from the equipment casing and
the seal chamber before startup. Vent casing and tubing of heat
exchanger (if applicable).