Pompetravaini SA Series Operating Manual Download Page 32

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Operating manual liquid ring vacuum pumps and compressors series TRH - TRS - TRM - TRV - SA & Systems type HYDROSYS - OILSYS

14 - PACKED STUFFING BOXES

DANGER!
Danger due to collision, crushing or abrasions. Possible contact with hazardous fluids, cold or warm. Wait for
the complete pump stopping before handling the unit. If the pump still contains some fluid it may suddenly
start to rotate once again. Take precautionary measures by draining the pump or closing the pipes by mean of
a valve. Remove protections only in case of maintenance. Operate only provided with apposite protective
devices.

Pumps fitted with packed stuffing boxes require packing flushing either from an external source or directly from the
pumped media through pump internal passages.
This liquid is necessary to remove the friction heat generated between the shaft and the packing.
The dripping quantity is a function of the pump size and of the pressure in the stuffing box housing.
In any event the liquid drops coming out of the stuffing box should not exceed a temperature of 60 - 70°C in relation to
handling a liquid at ambient temperature.



All adjustment operations must be performed with the

PUMP  NOT  RUNNING  following  the  safety  measures
given in chapter 2. After completion of the work ALWAYS
re-install the safety guards previously removed.
At  first  start  up  loosen  the  nuts  of  the  packing  gland
allowing a steady flow of liquid to drain out (see fig. 30).
After obtaining a steady flow of leakage gradually tighten
the gland nuts until attaining a steady dripping  within the
limit of the above recommended temperature.
A  few  hours  time  span  may  be  required  to  establish  a
steady dripping at low temperatures.
Packing  adjustment  is  required  when  the  liquid  leakage
increases.
When  adjustment  is  no  longer  possible,  the  packing
material should be replaced with new one.
Follow  the  “Disassembly  and  Assembly  Instructions”  to
replace the packing materials.
In  the  event  the  pump  remains  out  of  service  for  more
than 2 months it is recommended  to replace the packing
rings, prior to start-up.

15 – MECHANICAL SEALS

Purpose  of mechanical seals is to retain handled  product inside the  pump in the area  where the shaft exits the pump
casing.  Mechanical  Seals  can  be  of  many  different  materials,  types  and  configurations  (see  fig.  32-33-34  for  some
examples).
To  assure  maximum  reliability  and  safe  operation  Pompetravaini  evaluates  seal  choices  at  time  of  pump  selection  in
connection with customer’s requirements, application and liquid details.
In  the  case  of  self  lubricated  single  mechanical  seals  (API  Plan  01,  02  or  11,  see  fig.  32)  flushing  and  /or  pressure
system are not required, pump has been engineered to provide proper seal lubrication with pump operating pressure.

In  the  event  the  application  requires  increased  safety  margin  against  possibilities  of  product  leaking  through  a  single
type mechanical seal, it is possible to install two mechanical seals working simultaneously thus creating a safety barrier
from the pumped liquid.
There are two possible types of double mechanical seals: Back-to-Back (also kno

wn as “Opposite” type) API Plan 54,

see fig. 33 and in Series (also known as “Tandem” type) API Plan 52, see fig. 34.
Double mechanical seals Back-to-Back are generally selected where pumped liquid is absolutely not allowed to leak
from the pump. Double mechanical seals in Series are chosen where the pumped liquid may escape the pump toward
the pump exterior but it is controlled and contained in the closed seal loop but never to escape to the atmosphere.

Double mechanical seal installations require a flushing (buffer) liquid from an external source that is compatible with the
pumped product as well as the working conditions. Flushing liquid system is such as to guarantee adequate buffer liquid
pressure and temperature to the mechanical seals: seal flushing system with proper instrumentation and controls is of

LANTERN
RING

PACKING
RINGS

PACKED BOX FLUSHING

GLAND PACKING

ADJUSTING
BOLTS & NUTS

Fig. 30