Internals; Bush Materials; Maximum Temperature Of Internals; Operation Under Hydrodynamic Lubrication Conditions - Johnson Pump TG GS2-25 Instruction Manual

3.10 Internals

3.10.1 Bush materials

Overview of bush materials and application field
Material Code
Material
Hydrodynamical
lubrication
Corrosive resistance
Abrasive resistance
Dry running allowed
Sensitive to thermal choc
Sensitive to blistering in oil
Oil aging
Food processing allowed
(*) These are not absolute figures. Higher or lower values possible in function of the application,
expected lifetime etc.

3.10.2 Maximum temperature of internals

Because the overall temperature of TopGear GS pumps is limited to 200°C, there are no extra
temperature restrictions for internals.

3.10.3 Operation under hydrodynamic lubrication conditions

Hydrodynamic lubrication could be important criteria for bush material selection.
If the bush bearings are running under the condition of hydrodynamic lubrication there is no more
material contact between bush and pin or shaft and the lifetime cycle is increased importantly.
If there is no condition for hydrodynamic lubrication, the bush bearings make material contact with
pin or shaft and the wear of these parts is to be considered.
The condition of hydrodynamic lubrication is fulfilled
with the following equation:
Viscosity * shaft speed / diff.pressure ≥ K.hyd
with: viscosity [mPa.s]
shaft speed [rpm]
diff.pressure [bar]
K.hyd = design constant for each pump size.
A.0500.501 – IM-TGGS/05.01 EN (03/2013)
S C
Steel Carbon
if yes to maximum working pressure = 16 bar
if no 6 bar (*) 10 bar (*)
Fair Good
Slight None
No Yes
No No
No > 180°C
No No
Yes No (antimony)
B H U
Bronze Ceramic Hard metal
6 bar (*) 6 bar (*) 10 bar (*)
Fair Excellent Good
None Good Good
Moderate No No
No Yes dT<90°C No
No No No
> 150°C No No
No (lead) Yes Yes
TG GS pump size K.hyd
2-25 6000
3-32 7500
6-40 5500
15-50 6250
23-65 4000
58-80 3750
86-100 3600
185-125 2500
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