Double seals require a liquid in the seal chamber between the seal
inserts to provide lubrication. This barrier liquid must be supplied at a
pressure of 10 to 15 psi above seal chamber throat pressure to
activate the inboard seal. Before starting the pump, be sure that the
seal chamber is full of this lubrication and that all supply lines for this
liquid are in place and in operation.
Leakage from the outboard seal can be easily spotted. Leakage
through the inboard seal can be detected only by the loss of the bar-
rier (lubricating) liquid from between the seals. If leakage occurs, the
pump must be disassembled and the cause of leakage determined.
If you do not have the correct mechanical seal drawing, write to the
factory giving complete information on pump size, type, and serial
number and the correct seal drawing will be sent.
To avoid prolonged down time and facilitate rapid repair of dam-
aged pump parts, Dean recommends that the pump user maintain a
minimum stock of spare parts. If the pump service is critical or the
pump parts are of special materials, spare parts stock is even more
important to the user. Such spares inventory may extend from a
spare mechanical seal or seal parts through complete casing back
cover-impeller-bear ing housing assemblies prepared for immediate
insertion in the pump casing. Consult your Dean representative who
will assist you in selecting your spares stock.
Only Dean Authorized Service Parts shall be used.
ORDERING SPARE PARTS
Spare part orders will be handled with a minimum delay if the fol-
lowing information is furnished by the customer with the order:
1) Give the pump serial number and size. These may be found on the
pump name plate. The serial number is also stamped on the suc-
tion flange or the top edge of the bearing housing front flange.
2) Give the part name, part number, and material of part. These
should agree with the standard parts list.
3) Give the quantity of each part required.
4) Give complete shipping instructions.
SPARE PARTS
The preceding general and descriptive information for pH Series
pumps also applies to the pHP Series pumps. Special variations are
described below.
INSTALLATION
Suction piping to a self priming pump must be free of air leaks. If it is
not, the pump will not prime. Suction piping should be as short and
direct as possible. Long horizontal runs should be avoided. The less
suction piping, the less chance for air leaks. Flanged joints may be
coated with a rubber compound to avoid leaks at these points.
In applying a self-priming pump, consideration of the discharge pip-
ing is necessary. The air from the pump casing must be expelled
without being compressed substantially above atmospheric pressure.
Although a self-priming pump will prime against a small discharge
pressure, the priming time will increase and, if the pressure is high
enough, it will not permit the pump to prime.
If the pump expels air into an empty discharge system, there is more
than adequate volume available to contain the discharged air. If the
discharge line contains a check valve, it should be located a dis-
tance away from the pump so as to leave a volume in the discharge
line (between the pump and the check valve) equal to about half the
volume of the suction line.
If the check valve must be installed closer to the pump, install a
valved line from the pump discharge system back to the suction
source. This is left open during the priming cycle and closed when
priming is accomplished and during pumping. The check valve must
be installed in the pump discharge line downstream from the bypass
connection.
If the pump is fitted with a double mechanical seal a barrier liquid
must be supplied at a pressure 10-15 pounds above seal chamber
pressure when the pump is pumping.
If seal chamber packing is used it must include a lantern ring.
Sealing liquid compatible with the pumpage must be supplied under
pressure to the lantern ring connection in the seal chamber of the
pump.
Air leaks through the mechanical seal or packing will prevent pump
priming.
OPERATION
A self priming pump requires an initial prime after installation and
before normal operation. Be sure the end of the suction piping is
properly immersed in the liquid to be pumped. Remove the priming
plug in the top of the casing. Use a liquid which is compatible with
the normal pumpage. Pour this into the pump casing until the liquid
level stops rising. Any excess is going out of the pump through the
suction opening. Replace the priming plug and tighten it securely.
Start the pump and let it prime. Stop the pump. There will now be a
quantity of pumpage retained in the special casing. This will permit
the pump to reprime thereafter.
If during the initial prime or repriming, the pump runs without actual-
ly priming, there are two possible causes. The first of these is an air
leak in the suction piping. A very small hole is a major air leak and
will prevent priming. A leak of air into the seal chamber will likewise
prevent priming, air being constantly drawn into the pump.
MAINTENANCE
The maintenance of this pump is that described in the manual to
which this addendum is attached. Lubrication, installation, disassem-
bly and assembly instructions therein apply to the pHP pump. The
only difference is the shape of the casing.
Unlike the standard centrifugal pump casing, the pHP self priming
pump casing retains liquid. Care should be taken to drain the casing
thoroughly before the pump is removed from the line.
When a pump has been removed from the line and replaced, the
initial prime described above will be necessary before normal pump
operation.
INSTALLATION, OPERATION AND MAINTENANCE PHP SELF-PRIMING PUMPS
26
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