Starting (the centrifugal pump and axial How pump)
1) Open the suction check valve wide, opening at the same time the air vent on the top side.
2) Close the air vent as soon as liquid flows out of it.
3) Start the motor leaving the discharge valve closed.
4) Check that direction of rotation is as indicated by the arrow.
5) Slowly open the discharge check valve until operating requirements are reached.
6) Check on the ammeter that power requirements do not exceed. the motor possible rating.
7) Check tightness of the packing gland. Leaks must be reduced to a few drops which is required to prevent harmful heating of the packing and the shaft.
During operation
The pump output is to be controlled by operating on the discharge valve and never on the suction valve which must always remain wide open.
Stopping
After switching off the motor close the suction and the discharge valves of the pump.
IRREGULARITIES, THEIR CAUSES AND REMEDIES
Notes:
| loss | |
| trouble, obstruction | , |
| to deliver | , |
| insufficient | |
| to result from | |
| partially | |
| passage | |
| to rupture | , |
| to eliminate | |
| capacity | |
| leakage | |
| stuffing box |
| Symptom: | Cause: | Remedy: |
| Reciprocating pumps | ||
| Loss of suction | 1) Obstructions in the suction line. | Check suction valves. |
| 2) Air in the system. | Open the air cocks vents on the liquid end valve chest, leave them open until water flows out. | |
| Centrifugal pumps | ||
| A pump doesn't deliver any liquid | 1) Air in the pump case. | Let the air flow out. |
| 2) Insufficient speed of the pump. | Check the electromotor, bearings and gland box. | |
| 3) Excessive large pressure resulting from a partially clogged valve or some obstruction in the discharge line. | Check the valve and adjust it. | |
| 4) Clogged impeller passages. | Stop the pump and clean the impeller. | |
| 5) Ruptured suction line. | Stop the pump, eliminate leakages in the suction line. | |
| A pump operates at insufficient capacity | 1) Air leakage into the suction line or stuffing boxes. | Eliminate leakages. |
| 2) Mechanical defects such as worn wearing rings, impellers, stuffing box packing or sleeves. | Stop the pump, find the trouble and correct it. |
Lesson 12. AIR COMPRESSOR
Notes:
| troubleshooting | |
| to reduce | , |
| considerably | |
| filling | |
| occasionally | , |
| afterwards | |
| circumstance | |
| o.-ring | |
| connection | , |
| gasket | |
| sealing surface | |
| deposits | |
| flow rate | |
| visible | |
| further | , , : |
| deformed | |
| double | |
| adjoining plate | () |
| volume | , |
| to decrease | |
| respective | |
| hole | |
| to apply | |
| opposite side |
|
|
|
Maintenance and operating troubles and remedy
Maintenance involves the usual checks and overhauls common to reciprocating machinery, e.g. crankcase oil level, cooling water system, operating temperatures and pressures, etc. The suction and delivery valves are most troublesome. These valves automatic requiring a small pressure differential to operate.
The constant rapid opening and closing action of the valves may require seats to be refaced. Overheating, use of incorrect lube oil or the presence of dirt may result in sticking or pitting of the surfaces. The suction and delivery valves should be stripped and all parts carefully cleaned and examined and worn parts replaced and the valve seat and plate lightly lapped before reassembly, to ensure a good seal.
HEAT EXCHANGERS. PLATE TYPE.
