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.

If a pump has low head pressure, a lot of times it’s because it isn’t running a valve that matches the head pressure, which will cause a lot of problems. If the valve is undersized it might not be capable of allowing a high enough flow rate. If the valve is oversized the system will be very sensitive. A “small” change for the oversized valve would create a relatively large change for the system.

  • 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
  • The causes of water leaking into the crankcase include:
  • Water condensation
  • Worn out seals or crankcase packing
  • Clogged air breather(s)
  • Loose covers

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

These are some of the most popular questions we receive about pump valves and their components, and we hope you find them helpful when troubleshooting at your facility. Need additional help or can’t quite find the answer you’re looking for?

To browse our robust line of products built to resist these common pump failures, check out our online catalog.