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1. Precautions on operation
CAUTION
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Never operate pump dry or with suction side valve closed.
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Dry running possible model (D type of carbon bearing) can run dry (completely no liquid in pump)
continuously one hour max. However rubbing parts are worn in a short time which will result in pump
damage in the worst case if pump runs dry continuously exceeding one hour or if it runs dry repeatedly
although it is short time.
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After the pump ran dry, leave the pump one hour or more for cooling down to start it once again. If the
liquid flows into the pump just after the pump ran dry, ceramic parts are cracked due to heat shock.
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Check the direction of rotation of pump. Clockwise seen from motor fan is correct direction. If operated
in reverse, pump may be damaged.
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Stop the pump within one minute if it is operated in cavitation.
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Do not run pump with air sucking in.
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If magnet coupling is disconnected, pump can not transfer liquid. Stop pump within a minute and settle
the cause of disconnection before pump is started again.
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Intermittent operation
Frequent repetition of stop/start is not recommended. Stop/start repetition must be limited to six times
an hour. Frequent stop/run more than six times an hour may cause accelerated damage of parts and
lowered durability.
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Temperature change at starting, stopping and operating of pump must be within 80 deg. C.
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Fully close the discharge valve when pump is started to avoid water hammer.
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If the pump is operated with discharge valve closed for a long time, the liquid temperature inside the
pump rises, which may cause pump damage. Do not run the pump for more than one minute with
discharge valve closed.
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If power is interrupted while pump is running, switch off pump and close discharge valve.
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Pay attention so that discharge pressure can not exceed pump allowable pressure.
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Observe the allowable minimum flow rate. If the pump is operated below the allowable minimum flow
rate, bearing or rubbing parts may be seizured due to lack of lubrication and cooling.
Allowable min. flow rate
MDF-L250, 401 : 10 L/min.
MDF-L422, 423 : 20 L/min.
MDF-L425 : 50 L/min.
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When high temperature liquid is transferred, pump surface becomes very hot. Take protective measure
against burn.
Liquid temp.
Max. pump surface temp. (Amb. temp. 40 deg. C)
90 deg. C
80 deg. C
100 deg. C
90 deg. C
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Pump noise
MDF-L250: 75dB
MDF-L401, 422, 423, 425: 80dB