3
PENBERTHY
MODELS LL,LM, LH, ELL, GL, GH PLASTIC MATERIAL CONSTRUCTION JET PUMPS
INSTALLATION, OPERATION AND MAINTENANCE INSTRUCTIONS
4 INSTALLATION
Installation should only be undertaken by
qualified personnel who are familiar with
equipment of this type. They should have read
and understood all of the instructions in this
manual. The user should refer to the relevant
technical data sheet or the product proposal to
obtain dimensional information for the specific
size and model of jet pump.
Check Figures 1-6 for the location of operating,
suction and discharge connections to insure
correct hook up.
4.2 Effect of related piping and precautions
1. Plastic jet pumps can be installed and
operated in any position. For applications
handling gases, it is more desirable
to install models LM and ELL with the
discharge pointing down at 45° or more.
This prevents back splash of motive liquid
into the suction line.
2. Jet pumps should be installed with pipe and
fittings which provide minimum resistance
to fluid flow. Pipe line friction losses must
always be a consideration when estimating
jet pump performance.
3. It is recommended that provisions be made
for pressure gauge connections near the
operating inlet, suction and discharge
connections of the jet pump. If operating
difficulties are encountered at any time, it
may become necessary to install pressure
gauges to identify the problem.
4. When pumping liquids, suction piping
should be sized so that the velocity of the
liquid does not exceed 4 feet per second.
This is almost always obtained automatically
when the suction line is the same pipe size
as the suction connection.
5. Some back pressure is necessary to prime
models LL, LM and LH when pumping
liquids and when using the model LM
as an exhauster. A simple arrangement
which would provide the minimum
necessary back pressure is the installation
of two consecutive 90° elbows in the
discharge line.
6. When flow reversal into the suction must
be prevented, a check valve should be
installed in the suction line close to the jet
pump. Pressure drop created by the check
valve must be considered when applying the
jet pump.
7. Install a valve in the suction line if it is
desirable to:
a. Prevent contamination of suction fluid by
motive fluid at start up.
b. Prime a centrifugal pump.
c. Throttle suction flow.
8. When a gas operated jet pump is used to lift
liquids by suction or vacuum the jet pump
should be located as close to the level of
the liquid as practical. However, any liquid
entrained into the jet pump will cause the
jet pump to stop pumping, resulting in a
possible suction flow reversal.
9. Discharge piping should be sized as short as
possible and with the least number of turns
and restrictions. Discharge piping friction
losses must always be considered when
estimating jet pump performance. Increase
discharge line pipe size if necessary to
minimize loss.
4.1 Special handling of plastic material
jet pump
1. Use PTFE tape on all pipe connections
to reduce friction, improve sealing and
facilitate disassembly.
2. All threaded connections of jet pumps made
of polypropylene material must be back
welded or leaks may develop in time.
3. Connecting piping must be made of the
same material as the jet pump if the unit
will be exposed to changes in temperature.
Changes in ambient or fluid temperature
on connections of dissimilar materials can
cause loosening of joints resulting in leaks,
or tightening of joints resulting in rupture.
This is caused by the difference in thermal
expansion of the materials.
Examples of coefficients of thermal
expansion are as follows:
Kynar
®
…………………. 8x10
-5
in/in/°F
Polypropylene…………. 5x10
-5
in/in/°F
PVC…………………….. 3x10
-5
in/in/°F
Stainless steel………… 6x10
-5
in/in/°F
4. Thread the jet pump into piping per
instructions below to avoid upsetting
straight threaded joints, if any, and to avoid
damage to the plastic. Avoid over tightening.
a. Suction connection
Use ejector discharge for leverage when
connecting to suction.
b. Operating connection
Hold hex or flats on nozzle, if any, with
a wrench when attaching piping to
operating connection. If hex or flats are
not provided, then use existing suction
connection piping or temporarily thread
a short piece of pipe into the suction
connection to hold the jet pump.
c. Discharge connection
Hold flats, if any, with a wrench near the
discharge connection when attaching
piping to the discharge connection. If
flats are not provided, then use existing
suction connection piping, or a strap
wrench, or temporarily thread a short
piece of pipe into the suction connection
to hold the jet pump.
10. Do not impose system piping loads on the
jet pump. The unit is not designed to be a
load-bearing fitting.
11. All piping should be free of foreign materials
which could clog the jet pump.
