pumps and pumping systems  

SKD self-priming pumps


SKD self-priming rotodynamic pumps with side channel and centrifugal impeller before the first stage serve to pump liquids within the corrosion resistance limits of materials used for their construction. Liquids can contain trace amounts of solid particles up to 0.5 mm in size. SKD is a self-priming pump. Pump priming is necessary but there is no need to prime its suction pipeline with liquid.

SKD pumps can pump liquid with a minimum excess pressure over boiling point. Small NPSHr net positive suction head in pumping system and very good priming ability are of particular advantage.
SKD pumps are designed to pump crude-oil derivative fuels and propane-butane mix, without gaseous phase fraction.

Technical specifications

capacity 0,2 ÷ 30 m3/h
delivery head up to 310 m *
pumped liquid temperature -40oC ÷ +180oC
liquid density up to 1,3 kg/dm3
liquid viscosity up to 150 mm2/s
mass 37,0 ÷ 436,0 kg
motor power 0,25 ÷ 30,0 kW
rotation speed 1450 obr/min (50 Hz) and 1800 obr/min (60 Hz)
rotations direction clockwise, looking on the pumps from drive side
*)  Delivry head is lowered by 10-20% for hot liquids from +70oC do +110oC.

Product marking structure

0 8
1 6 1 0
0 0 2
a a
c c
e1 e2 e3 e4
i i i

a a - classification group
f - product variety ( D - fot work with deep suction)
b - pump type/size (2 ÷ 8)
c c - pump type/dimension (number of stages) (01 ÷ 08)
d - pump material execution as in MATERIAL EXECUTION
e1 e2 e3 e4   - pump constructional execution as in CONSTRUCTIONAL EXECUTION
h - supply completeness as in SUPPLY COMPLETENESS
i i i - motor type
k - product cosmetics as in PRODUCT COSMETICS (protective coatings)

Material execution of SKD pumps

   SKD pumps are produced in eight material executions ***

Pump elements Material "d"
1 2 3 4 5 6 ** 7 8
Casing gray cast iron tin bronze gray cast iron gray cast iron ductile cast iron freezeproof ductile cast iron cast carbon steel austenitic cast steel
Members gray cast iron chromium cast iron gray cast iron chromium cast iron gray cast iron freezeproof ductile cast iron cast carbon steel austenitic cast steel
Impeller tin bronze tin bronze ductile cast iron tin bronze tin bronze tin bronze tin bronze special austenitic cast steel
Shaft stainless steel acid-proof steel stainless steel acid-proof steel stainless steel stainless steel stainless steel acid-proof steel
Shaft seal soft-cord seal *
mechanical front seal *
* seal material selection depends upon medium pumped
** minimum working temperature -40oC
***    pumps can be made of other materials (high-nickel cast iron, cast steel) but this requires technical and trade agreements

Constructional execution

Constructional execution No
e1 e2 e3 e4
Constructional execution SKD pump
2 3 4 5 6 7 8
1030 Pump with cord seal and chamber for -30oC ÷ +70oC liquid temperature  
1040 Pump with cord seal and chamber for -30oC ÷ +70oC liquid temperature            
1110 Pump with single front V-type seal for -30oC ÷ +70oC liquid temperature
1130 Pump with single front seal of US-type for -30oC ÷ +70oC liquid temperature  
1140 Pump with single front seal of VB-type for -30oC ÷ +70oC liquid temperature  
1160 Pump with single front seal of 502-type for -40oC liquid temperature
1200 Pump with single front seal of 502-type and repair kit, for -30oC ÷ +70oC liquid temperature
1360 Pump with single front seal of V-type with quenching for -30oC ÷ +70oC liquid temperature
1380 Pump with single front seal of US-type with quenching for -30oC ÷ +70oC liquid temperature  
1390 Pump with single front seal of VB-type with quenching for -30oC ÷ +70oC liquid temperature  
1400 Pump with single front seal of 502-type with quenching for -30oC ÷ +70oC liquid temperature
1430 Pump with single front seal of 502-type with quenching and repair kit for -30oC ÷ +70oC liquid temperature
1600 Pump with double front seal in BACK TO BACK V + V-type System with barrier liquid
for -30oC ÷ +70oC liquid temperature
1610 Pump with double front seal in BACK TO BACK V + VB-type System with barrier liquid,
for -30oC ÷ +70oC liquid temperature
1630 Pump with double front seal in BACK TO BACK V + US-type System with barrier liquid
for -30oC ÷ +70oC liquid temperature
1640 Pump with double front seal of BED-type for -30oC ÷ +70oC liquid temperature  
1650 Pump with double front seal of BED-type with buffer/barrier liquid system
for -30oC ÷ +70oC liquid temperature
5160 Pump with single front seal of 502-type for -40oC ÷ +70oC liquid temperature
5640 Pump with double front seal of BED-type for -40oC ÷ +70oC liquid temperature  
5650 Pump with double front seal of BED-type for -40oC ÷ +180oC liquid temperature  

Supply completeness

1 - Pump with free shaft end.
2 - Pump with coupling.
3 - Pump with coupling and foundation plate.
5 - As in 3 plus electric motor.

Product cosmetics

1 - Standard
2 - Special


At SKD pumps suction side there is an axial inlet of increased diameter, outlet opening at the discharge side is directed vertically upwards. Before the first stage at the suction side a centrifugal impeller and stator are applied. Pump stages are typical circulation pump stages with side channels and open impellers. Encased ball bearings and an appropriate shaft seal are located at the pump discharge side. Depending on pump purpose and constructional execution a front seal is used, among others things, to ensure total tightness.

The front seal can be lubricated and flushed with pumped or outside liquid. In LPG-execution pumps a special sealing LOCTITE-573 mass is applied, in other executions 0.11 mm thick gaskets are used between stages. LPG pumps are subject to a special test for tightness and mechanical strength. The SKD pump is additionally equipped with a diffuser installed on its suction housing, and with a circulation pipe through which the slide bearing placed in pump stator is lubricated by liquid contained in the pump when it pumps air from suction pipeline.


  • many years of reliable operation and easy access to replacement parts guaranteed,
  • execution of individual requirements and products adjusted to customer's needs,
  • permanent technical supervision as well as guarantee and post-guarantee service,
  • low procurement and operation costs,
  • relatively long life in difficult operation conditions,
  • high resistance against changeable climatic conditions, including operation in extreme ambient conditions,
  • cooperation with underground tanks.

Technical requirements for hydraulic system in the liquid hydrocarbons pumping process (propane-butane liquefied gas)

Liquid compounds like propane-butane and other mixtures are subject to specific laws of physics. Propane-butane liquefied gas is a mixture of upper saturated hydrocarbons characterized with high vapour pressure dependence on ambient temperature. In normal physical conditions (1013 hPa, 20oC) they are heavier than air (gas density is higher than air density) and when their outflow is uncontrolled, they trail close to the ground surface filling all hollows in. In its volatile phase the gas is highly inflammable and when mixed with air creates a very dangerous explosive mixture. In its liquid phase it is lighter than water and, when evaporating, floats on the surface. Passing from liquid to the volatile phase in a free space begins at -30oC (50/50 propane/butane mixture). To keep the propane-butane mix in liquid state during the whole distribution process and especially at the pump first stage impeller inflow, liquid pressure must be subjected to any excess pressure Ap in relation to its value determined from the liquid evaporation curve.

Pumps working conditions

To ensure undisturbed pumping process and pump operation, the following basic equation conditions must be fulfilled:

Hzs = -(NPSHr + hs)  [m]

hshydraulic losses in suction pipeline (m)
Hzs geometrical inflow height (n)
NPSHr   required net positive suction head as specified by the manufacturer to guarantee proper pump operation (m)

When the required Hzsvalue calculated for the complex (LPG station) in the technical project is not met, it will lead to pump destruction. Destruction of the front mechanical seals on the pump shaft, pump slide bearing and the whole hydraulic system (impellers and members) is likely. A properly designed pumping system must fulfil the conditions:

NPSHav > NPSHr  [m]

NPSHav   available net positive suction head in pumping system [m]

Hzs inflow height can be optimized through hs hydraulic losses reduction in suction (inflow) pipeline and this is the only parameter in which we can interfere.

Technical requirements

When performing the installation, the following technical requirements should be observed:

  • strive to limit flow resistance in the suction pipe to the minimum,
  • do not change the pipe section area just before the pump through the installation of elbows, filters, dampers or reducers,
  • to calm gas stream down, a pipe section before a pump of 20 pipeline diameters length is absolutely necessary.

Inflow height Hzs [m] specified on the basis of geometrical formula must be unconditionally kept. The ball valve at the pump discharge side must be half-open during pump switch-off. When the ball valve is fully open a danger of total gas evaporation exists (pump will operate off its catalogue operating range). Both ball bearings: in the pressure equalization conduit at the suction side to the tank and at the suction side must be fully open. One should be absolutely sure that the pump is filled with liquid gas during the pump start up.

To ensure that the pump is primed with gas, fitting a ball valve downstream in discharge, flow meter or flow gauge conduit is recommended,

  • suction pipeline should be as short as possible so as to protect the whole pumping system against outside heat,
  • gas flow velocity in suction pipeline should not exceed 1 m/s,
  • if liquids are contaminated, a filter should be installed in the pipeline,
  • free filter crossing area must be at least three times larger than rated pump inlet diameter,
  • the filter should be periodically cleaned,
  • suction pipeline minimum diameter should be at least equal to pump connector diameter (dr>ds) on the whole pipeline length (from tank outlet to pump connection),
  • gas flow direction is marked on the pump with arrows,
  • the pipe system must be made in such a way which enables stress-free pipe to pump connection (use of compensators is recommended),
  • the pipe system should be carefully cleaned from welding chips, file dust, rust and similar foreign matter before its connection to the pump,
  • when the pump is used in an explosion-endangered area, the equipment used must fulfil the appropriate safety rules in force,
  • motor rotation direction must be the same as pump rotation direction (as shown on pump suction housing).

Observe local regulations on electrical equipment,

  • motor rotation direction: left when looking at the pump from motor side,
  • after pump is set on the foundation and line-connected, check coupling setting.

Example schematic diagram of SKD pump application in cooperation with underground tank

  1. - storage tank
  2. - inflow suction pipeline
  3. - gas phase pipeline
  4. - gas phase separator
  5. - discharge pipeline
  6. - pump
  1. - discharge pipeline
  2. - bypass valve
  3. - pressure gauge
  4. - orifice plate
  5. - valve

Note: Suction pipeline must be insulated against warming by sunbeams.

SKD pumps shaft sealing systems

      System of cord seal with chamber
System of front single seal       
      System of front single seal with quenching
System of front double seal in BACK TO BACK arrangement with barrier liquid       

Hydro-Vacuum S.A.
ul. Droga Jeziorna 8
86-303 Grudziądz
tel. 56 45 07 415
fax. 56 46 25 955
Copyright © Hydro-Vacuum S.A.

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