Piping; Accessories - Johnson Pump MCHZ Instruction Manual

3.4
3.5
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Piping

• The piping to the suction and delivery connections must fit exactly and must not be
subject to stress during operation.
• The passage of the suction pipe must be amply dimensioned. This pipe should be as
short as possible and run towards the pump in such a way that no air pockets can
arise. If this is not possible, a venting facility should be provided at the highest point of
the pipe. If the inside diameter of the suction pipe is larger than the suction connection
of the pump, an eccentric reducer should be applied to prevent air pockets and whirls
See figure 3.
Figure 3: Eccentric reducer to suction flange.
• The maximum allowable system pressure is stated in paragraph 10.2 "Permissible
pressure and temperature". If there is a risk that this pressure might be exceeded, for
instance because of an excessive inlet pressure, appropriate measures should be
taken by mounting a safety valve in the piping.
• Sudden changes in the rate of flow can lead to high pressure impulses in the pump
and the piping (water shock). Therefore, do not use quick-acting closing devices,
valves etc.

Accessories

• Fit any parts that may have been supplied separately.
• If the liquid does not flow towards the pump, fit a foot valve at the bottom of the
suction pipe. If necessary, combine this foot valve with a suction strainer to prevent
impurities from being drawn in.
• When mounting, place temporarily (for the first 24 operating hours) a fine gauze
between suction flange and suction pipe to prevent internal pump parts from being
damaged by foreign matter. If the risk of damage continues to exist, fit a permanent
filter.
Installation
MCHZ/EN (0912) 4.2