BLACKMER LDF1A, Installation, Operation And Maintenance Instructions

501-F00    Page 5/12 

OPERATION 

Do not operate 

without guard 

in place 

OPERATION WITHOUT GUARDS IN 
PLACE CAN CAUSE SERIOUS 
PERSONAL INJURY, MAJOR 
PROPERTY DAMAGE, OR DEATH. 

Hazardous pressure 

can cause serious 

personal injury or 

property damage

FAILURE TO RELIEVE SYSTEM 
PRESSURE PRIOR TO PERFORMING 
PUMP SERVICE CAN CAUSE SERIOUS 
PERSONAL INJURY OR PROPERTY 
DAMAGE.

SYSTEMS WITH METERS 

WILL STILL BE PRESSURIZED EVEN 
AFTER THE HOSE IS EMPTIED

Hazardous pressure 

can cause serious 

personal injury or 

property damage 

DISCONNECTING FLUID OR PRESSURE 
CONTAINMENT COMPONENTS DURING 
PUMP OPERATION CAN CAUSE 
SERIOUS PERSONAL INJURY OR 
PROPERTY DAMAGE.

Hazardous pressure 

can cause personal 

injury or property 

damage 

PUMPS OPERATING AGAINST A 
CLOSED VALVE CAN CAUSE SYSTEM 
FAILURE, PERSONAL INJURY AND 
PROPERTY DAMAGE  

PRE-START UP CHECK LIST 

1.  Check the alignment of the pipes to the pump. Pipes 

should be supported so that they do not spring away or 
drop down when pump flanges or union joints are 
disconnected. 

2.  Check the entire pumping system to verify that the proper 

inlet and discharge valves are fully open, and that the 
drain valves and other auxiliary valves are closed. 

3.  Install suction and discharge pressure gauges on the 

pump in the threaded connections provided. These can 
be used to check actual suction and discharge conditions 
after pump start-up. 

4.  Check the wiring of the motor. 
5.  Briefly start the pump to verify proper rotation direction. 
 
 

START UP PROCEDURES 

NOTICE: 

CONSULT THE "GENERAL PUMP TROUBLESHOOTING" 
SECTION OF THIS MANUAL IF DIFFICULTIES DURING 
START UP ARE EXPERIENCED. 

1.  SLOWLY build pressure in the pump. 

2.  Start the pump. Priming should occur within one minute. 
3.  Check the suction and discharge pressure gauges to see 

if the pump is operating within the expected conditions. 

4.  Check for leakage from the piping and equipment. 
5.  Check for excessive noise, vibration or overheating of the 

pump, reducer, and motor. 

6.  If possible, check the flow rate. 
7.  With the manual valve in the bypass line OPEN, check 

the

pressure setting of the relief valve by slowly closing a 

valve

in the discharge line and reading the pressure 

gauge. As

the valve in the discharge line is closed, the 

pump

discharge pressure will rise to a maximum value, 

then drop

back slightly. Use the maximum pressure to 

determine the

valve setting. This pressure should be 10 - 

20 psi (0.7 -1.4

bar) higher than the maximum system 

operating

pressure. If adjustments need to be made, 

refer to the

"Relief Valve Setting and Adjustment" section 

of this

manual. 

 
8.  The external bypass valve must be set at least 25 psi 

(1.7 bar) lower than the internal pump relief valve. NOTE: 
The normal operating pressure must be at least 5 - 15 psi 
(0.3 -1.0 bar) less than the external bypass valve setting.  

NOTE: 

If the pump is operated with both the discharge

line 

and bypass line closed, the pump will recirculate fluid

through 

the internal relief valve, causing cavitation and

excessive 

wear on the pump. The pressure gauge may

also read lower 

than with normal operation. 
 
 

RELIEF VALVE SETTING AND 
ADJUSTMENT 

The relief valve pressure setting is marked on a metal tag 
attached to the valve cover. Generally, the relief valve should 
be set at least 10 - 20 psi (0.7 - 1.4 Bar) higher than the 
operating pressure, or the external bypass valve setting. 

DO NOT adjust the relief valve pressure setting while the 
pump is in operation.  

1. 

To INCREASE the pressure setting,

 Loosen the locknut, 

and turn the adjusting screw 

inwar

d, or clockwise.  

Retighten the locknut 

2. 

To DECREASE the pressure settin

g, Loosen the 

locknut, and turn the adjusting screw 

outwar

d, or 

counterclockwise. Retighten the locknut 

Hazardous pressure 

can cause serious 

personal injury or 

property damage 

INCORRECT SETTINGS OF THE 
PRESSURE RELIEF VALVE CAN CAUSE 
PUMP COMPONENT FAILURE, 
PERSONAL INJURY, AND PROPERTY 
DAMAGE.