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Other important considerations for dosing pumps in ex-zones
Page 22
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Piston dosing pumps may not be used for combustible media.
Where it is impossible to avoid the use of piston pumps, additional control measures
should be used to ensure the required level of safety: flow controller + piston leakage
controller, and an additional temperature controller on the dosing head for media with
critical friction characteristics.
•
Hydraulic diaphragm pumps are perfectly suitable, however it is compulsory to have
those whose construction includes diaphragm-rupture controller Ex "i" and flow
controller.
•
Diaphragm pumps with mechanically linked diaphragm, e.g. MTMa..., TZMa..., Sigma's
S1Ba..., S2BaHM..., S3Ba: no additional measures are necessary, although it is essenti-
al to use the construction with diaphragm-rupture indicator, in the Ex "i"* construction.
•
Dosing pumps used in ex-zones must be fitted with an appropriate safety relief valve
on the output side of the dosing pump (serves to protect against overheating resulting
from overloading and arcing due to interruption of drive components as a result of
overloading).
•
Piston dosing pumps are designed for use in temperature class T3.
The pumps are suitable for use in T4 if they are fitted with an additional flow controller
on the output side (serves to protect against a rise in temperature resulting from dry
running) or with an appropriate temperature controller.
•
Similarly, dosing pumps whose diaphragm is driven hydraulically must be fitted with a
temperature or flow controller for use in T4. (The internal relief valve protects against
overheating in the event of extended operation.) Without this protection, temperature
class T3 is applicable.
•
With different temperature classes being available for different components, the
possible application of the entire pump corresponds to the component with the lowest
temperature class.
9.7
Maintenance
WARNUNG
•
You should make regular checks (on leakages, noise, temperatures, odours, etc.) to
ensure general regular operation, particularly with regard to the actuator and bearing.
•
Do not allow the pump to overheat due to a lack of oil!
For lubricated dosing pumps, you should make regular checks to ensure sufficient
lubricant is present, e.g. by checking the level of lubricant, visual check for leakages,
etc. If oil is leaking, you must locate the point of leakage immediately and eliminate
the cause of the leak.
•
Check the regular operation of the relief valve behind the pump!
In the event of a fault in areas of operation where there is a risk of explosion, the relief
valve must prevent the gears from being overloaded and overheating!
•
When cleaning plastic components, you should ensure that no electrostatic charge is
created through excessive friction. - see warning sign
•
The following applies to all dosing pumps when metering combustible media: Start up
and drain only under the supervision of an appropriately qualified person.
•
Expendable parts, such as bearings, must be replaced when there are visible signs of
unacceptable wear. (It is not possible to calculate the nominal service life for lubricated
bearings.)
•
Original spare parts must be used as replacements.
•
Inspection and repair must be carried out in compliance with DIN EN IEC 60079-17
and should only be done by "experienced personnel with the necessary expertise"
(section 4.2).
•
These measures are prescribed by ProMinent as the minimum required for protection.
If the operator is aware of other risks, it is his responsibility to eliminate these by
implementing the appropriate measures.
ProMinent
ProMinent
®
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