At Triangle Pump Components, we take pride not only in manufacturing the highest quality pumps for a diverse range of industries, but also in being the go-to resource for all of your pump questions. To help you begin troubleshooting an issue, here are some of the common questions customers ask us about getting to the root cause.
- Low volumetric efficiency, or the failure to deliver rated capacity and pressure, can be caused by any number of conditions. Common sources include:
- Pockets of air or vapor in the inlet line
- A power pump capacity that’s greater than the charge pump capacity
- Air or vapor trapped above the inlet manifold
- Air leaks in the liquid supply piping system
- Air or gas entrained in liquid
- Foreign objects preventing the pump inlet or discharge valve(s) from closing or blocking liquid passage
- Incorrect drive ratio or motor/engine speed
- Loose belts, valve covers, cylinder heads, or bolts in the pump inlet manifold
- Worn valves, seats, liners, piston rings, or plungers
- A safety relief valve that’s partially held open or failing to maintain pressure
- A bypass valve that’s partially held open or failing to maintain pressure
- Blown liner gasket
- Insufficient NPIPA (net positive inlet pressure available)
- Internal liquid bypass
- Vortex in the supply tank
- Insufficient power delivery from the motor
Common cases of low NPIPA include:
- Partially clogged inlet lines
- Excessive liquid vapor pressure and pumping temperature
- Restricted inlet pipe fittings
- Too long of an inlet line
- Too many pipe fittings
- Too small of an inlet line
- Too low of static inlet head
- Too low of atmospheric pressure
The main drivers of pump overloads include:
- Excessive pump speed
- Low voltage or other electrical problems
- Trouble with engine, turbine, gears, or other related equipment
- Excessive discharge line pressure
- Clogged discharge lines or closed/throttled valves in the discharge line
- Incorrectly sized liner for the application
- Improper bypass conditions
- Over-tightened stuffing box glands on adjustable packaging
Stuffing box leakage primarily stems from the wrong size packaging or worn out parts including:
- Packing
- Rods or plungers
- Stuffing boxes
- O-ring seals
The three leading causes of stud failure are:
- Excessive discharge pressure
- Improper torqueing of nuts
- Shock overload from pump cavitation
Common causes of noisy valves include:
- Weak or broken valve springs
- Pump cavitation
- Air leaks in the inlet piping or loose bolts in pump inlet manifold
- Air trapped above the inlet valve
Common causes of inlet or discharge line vibration include:
- Inadequate piping support
- An inlet line that’s too long or small in diameter
- Too many bends in the inlet line
- Multiple pump installations operating in phase
- Obstruction under valve(s)
- Worn out packing
- Operating above the recommended pressure or speed
- Low NPIPA
Noisy operation can include both liquid and mechanical knocking, though the latter is much rarer on new installations. Causes of excessive noise include:
- Loose pistons or plungers
- Amplified valve noise through a power end
- Pump cavitation
- Air leaking into the inlet pipe
- Loose bolts in the pump inlet manifold
- Hydraulic noise in liquid end
- Loose or worn crosshead pins and bushings
- Loose connecting rod cap bolts
- Worn crosshead or connecting rod bearings
- Excessive main bearing end play
- Worn gears or chains
- Gears or chains that are out of line
- Backwards running pump
- Partial loss of prime
- Shocks in the piping system
- Water in the power end crankcase
- Poorly supported piping, abrupt turns in piping, misaligned piping, or piping that’s too small
In addition to normal wear over time, packing failure is caused by:
- Improper materials or lubrication
- Excessive gland tightening in adjustable packing
- Dirty liquid or environment
- Plunger or piston misalignment
In addition to normal wear over time, valve failure is caused by:
- Pump cavitation
- Abrasives in the fluid
- Incompatibility of valve components with corrosive liquids
- Electrolysis
- Improper installation including driving on the valve stem, improper torque on the jam nut, or valve seat/deck that isn’t thoroughly cleaned and dried
Common causes of plunger failure include:
- Thermal shock from cold water hitting the plunger
- Packing that’s too tight
- An inlet valve that becomes disassembled while the pump is in operation
- Improper tightening causing the stuffing box gland to rub on the plunger
- Dirty liquid or environment
- At times, liquid won’t be delivered because:
- The pump is not primed
- Air or vapor pockets are in the inlet line
- There’s a clogged inlet line
- Inlet valves or discharge valves are held open
- There are loose bolts in pump inlet manifold
- Valve velocities are too high
Cavitation often results from:
- Too low NPIHA (Net Pressure Inlet Head Available)
- Liquid not delivered to pump inlet connection
- Excessive stuffing box leakage
- Too high NPIHR (Net Pressure Inlet Head Required)
Leaks at the cylinder head or valve cover are caused by:
- Running above the recommended pressure
- Loose cylinder head or valve cover
- Damaged gasket
Leaks at the cylinder head or valve cover are caused by:
- Running above the recommended pressure
- Loose cylinder head or valve cover
- Damaged gasket
Oil leaks from the crankcase are caused by:
- Oil levels that are too high
- Worn out seals or crankcase packing
- Loose crankcase cover
The power end can overheat as a result of:
- A pump running backward too slowly
- Insufficient or excessive oil in the power end
- Incorrect oil viscosity
- Operating above the recommended pressure
- Bearings that are too tight
- Belts that are too tight
- One or more of the cylinder’s discharge valves being stuck open
- Insufficient cooling or ventilation
- Low pump speed
- Excessive liquid end packing tightening on adjustable packaging