Flowserve WUC Worthington - Manual (Page 20)

WUC USER INSTRUCTIONS ENGLISH - 07/14
Page 20 of 52
Fig. 2
4.5.2.3 Gas Coffer Dam design
To prevent icing of the mechanical seal, all WUC
pumps handling liquids at temperatures below -50°C
(60°F) are fitted with a gas coffer dam.
Prior to start-up the pump must be vented through
connection N3 to ensure the pump will be fully filled
with liquid.
Pumps in stand-by (idle) shall be continuously vented
through connection N5 (Fig.3), to avoid build-up of
vapor-bubbles or gas
Standard
design
Description
N1 Suction nozzle
N2 Discharge nozzle
N3 Connection for venting of can
N5
Connection for balancing line of
gas coffer dam
M.S Mechanical seal
G.C.D Gas Coffer Dam
Fig. 3
4.5.3 Recommended venting for flashing liquid
Flashing liquids are medium that vaporize at
atmospheric pressure and ambient temperature.
Gases can be liquefied by pressurization and/or
cooling.
Flashing liquids pose a potential threat for problems
caused by vaporization (flashing). If the pumped
liquid is close to its evaporation point, the whirl¬ing
motion at the entry of the pump hydraulic may cause
evaporation or degassing of the dissolved contents.
These gases would collect in the upper part of the
headstock and disturb the flow.
Therefore proper venting is most critical when
operating pumps handling liquids listed in Table 1
Samples of flashing liquids
boiler feed water
condensate
hot water (above 80°C)
hydrocarbons (CnHn)
liquids with high gas content
LPG
liquids with density lower than 650 kg/m³
Table 1.