Finish Thompson DB3, 4, 5 & 5.5 Series - Manual (Page 5)

Installation/Operation Precautions
CAUTION: This pump should never be operated without liquid in the casing . It is recommended that run dry protection be used .
Optional electronic power monitors are available to help protect against run dry . If the pump has a PTFE or ceramic bushing,
IT CANNOT BE RUN DRY WITHOUT CAUSING DAMAGE TO THE PUMP . However, the pump can operate without liquid in the casing
if the pump has a carbon bushing . The exact length of time the pump can operate dry with a carbon bushing varies with operating
conditions and the environment .
CAUTION: Never start or operate with a closed suction valve . Never operate with a closed discharge valve .
CAUTION: Always provide adequate NPSHa (net positive suction head available) . It is recommended to provide at least 2 feet (61
cm) above the NPSHr (net positive suction head required) .
DB3, 4, 5 & 5.5 Capabilities
Maximum Working Pressure: 60 psi (4 .1 bar)
Maximum Viscosity: 50 cP
Maximum Temperature: Polypropylene: 180º F (82º C); PVDF: 220º F (104º C)
NOTE: Maximum temperature is application dependent . Consult a chemical resistance guide or the chemical manufacturer
for chemical compatibility and temperature limits .
Solids: Maximum particle size is 100 microns for slurries and 1/64” ( .4 mm) for infrequent particles . Maximum hardness is 80 HS .
Maximum concentration is 10% by weight . Pumping solids may lead to increased wear .
Minimum Allowable Flow Rate: Do not allow the flow rate to drop below the minimum flow rate listed in the chart below .
3450 rpm 2900 rpm
.25 gpm
( .95 lpm)
.95 lpm
( .25 gpm
Maximum Allowable Motor Power: Do not exceed the maximum power rating for the pump coupling .
Standard coupling for the DB3,4, and 5 is 4 pole . Maximum motor power is 1/4 horsepower ( .18 kW) .
Standard coupling for the DB5 .5 is 6 pole . Maximum motor power is 1/2 horsepower ( .37 kW) .
Unpacking and Inspection
Unpack the pump and examine for any signs of shipping damage . If damage is detected, save the packaging and notify the carrier
immediately .
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