HAMMELMANN B7.02502.0210, Operating Instructions Manual

Page: 296 / 311

Page 5
5.7 Pump operating mode
Make sure that the pump is always started up with the suction-side shut-off valve fully open and the discharge-side
shut-off valve slightly open. However, the pump can also be started up against a closed swing check valve. Only after
the pump has reached full rotational speed shall the discharge-side shut-off valve be adjusted to comply with the duty
point.
Pump operation with closed shut-off valves in the suction and / or discharge pipes is not permitted. In this
case, there is a risk of the pump casing reaching a high surface temperatures after a very short time, due to a rapid
temperature rise in the pumped fluid inside the pump.
Additionally, the resulting rapid pressure build-up inside the pump may cause excessive stresses on the pump
materials and even cause it to burst.
The minimum flows indicated in the relevant pump operating manuals refer to water and water-like liquids. Longer
operating periods with these liquids and at the flow rates indicated will not cause an additional increase in the
temperatures on the pump surface. However, if the physical properties of the fluids handled are different from water,
it is essential to check if an additional heat build-up may occur and if the minimum flow rate must therefore be
increased.
The calculation formula below can be used to check if an additional heat build-up may lead to a dangerous
temperature increase at the pump surface.
To = Tf +
∆ϑ
∆ϑ
= ((g * H) / (c *
η
))*(1 -
η
)
c Specific heat of liquid [J / kg K]
g Acceleration due to gravity [m
2
/s]
H Pump head [m]
Tf Temperature of fluid handled [º C]
To Temperature of casing surface [º C]
η
Pump efficiency [-]
∆ϑ
Temperature difference [º C]
5.8 Temperature limits
In normal pump operation, the highest temperatures are to be expected on the surface of the pump casing, at
the shaft seal, at the bearing areas and at the pump shaft end in close coupled executions.
Unless the pump is equipped with an additional heating facility, the surface temperature at the pump casing will
correspond to the temperature of the fluid handled, assuming that the pump surface is freely exposed to the
atmosphere.
In any case, responsibility for compliance with the specified fluid temperature (operating temperature) lies with the
plant operator. The maximum permissible fluid temperature depends on the temperature class to be complied with.
The following limits for the maximum permissible fluid temperature must be observed for the individual temperature
classes as per EN13463-1 given below (temperature increase in the shaft seal area, if any, has been taken into
consideration):
Temperature classes Permissible Max. permissible fluid
as per EN 13463-1: surface temperature for compliance
temperature with temperature class
T5 100 º C 80 º C
T4 135 º C 115 º C
T3 200 º C 180 º C
T2 300 º C 280 º C
T1 450 º C Temperature limit of pump
Safety note:
The permissible operating temperature of the pump in question is indicated in the technical data. If the pump is to be
operated at a higher temperature, the technical data are missing or if the pump is part of a pool of pumps, the
maximum permissible operating temperature must be requested from the pump manufacturer.
HAMMELMANN Code no.: 04.03226.0769
Type 32-200