Most industries have several pumps performing a variety of functions that are integral to the successful operation of the plant. If a pump malfunctions, it can be the cause of an entire plant shut down. As a leading manufacturer and supplier of progressive cavity type screw pumps and zero leak Rota pumps, Risansi emphasizes on doing proper pump maintenance at site to ensure long-life of pumps. Pumps maintenance is done in order to improve system reliability. Proper maintenance of a pump is important to ensure its trouble free and long service life. To keep pumps running properly, a regular maintenance schedule should be implemented and followed.

Maintenance can be of following types

• Preventive or predictive- Predictive
  maintenance (PdM) techniques are
  invaluable for keeping pump
  reliability high and life-cycle costs
  low. Diagnostic monitoring during
  pump operation such as vibration
  analysis, electrical monitoring, and
  lubricant analysis often reveal early
  signs of trouble
• Conditional Monitoring- Condition
  monitoring is a process used to
  monitor the condition of the pump
  which ultimately reduces the time
  required to identify and rectify the
  fault and increases the efficiency of
  the pump. It monitors parameters
  like temperature, vibration etc
• Periodic -Periodic maintenance is a
  strategy that requires maintenance
  tasks such as external cleaning of
  pump, leakage checks tightening of
  nuts & screw etc. to be performed
  at set time intervals while the pump
  is operational
• Breakdown- Breakdown
  maintenance is required when the
  pump completely breaks down and
  needs repair to resume operation. It
  can be planned and unplanned
  both

Important Check Points

One must ensure to check and follow below points for smooth maintenance of pumps

• DETERMINE MAINTENANCE
  FREQUENCY-A correct
  maintenance strategy is often based
  on manufacturers’/ OEM’s
  recommendations. Select a time
  when the system is down. Pump to
  be overhauled at regular intervals.
  It is advisable to overhaul the motor
  also along with the pump.
• OBSERVATION IS KEY- A close
  observation of pump is important
  while it is running.
• Indication of pump parts wear can
  be identified from abnormal noise,
  vibration, loss of capacity, reduction
  in discharge pressure, leaks etc.
  Inspect internal parts carefully while
  overhauling
• Internal clearances in the pump,
  which are vital for its proper
  function. Acceptable wear can be
  determined only by experience of
  the actual application.
• Pump Vibration-Vibration imparts
  forces on each part of the seal
  components. Vibrations may be due
  to worn bearings, improper grouting
  and poor foundation of pump
• SAFETY FIRST- It is important to
  make sure that pumps are shut-down
  before performing the maintenance
  activities. Mechanical, electrical, as
  well as hydraulic isolation is
  important.
• MECHANICAL INSPECTION-
  • Check that foundation points are
  fixed properly. It is important to
  periodically inspect foundation
  bolts, couplings and performance of
  the pump as conditional monitoring
  to avoid breakdown maintenance.

MAINTENANCE STRATEGIES AT SITE

• Check mechanical seal, gland
  packing, flanges or other joints of
  pump for leakage
• Check the condition of small parts
  that are prone to wear and tear
• Replace small parts on time to ensure
  the complete life of large parts is
  availed.
• Wear of spare parts greatly depends
  on the pumping medium. Pump
  screw is lubricated by the pumping
  liquid itself. Please refer to our
  previously published article in June
  2021 issue. So it is important to
  choose the correct RPM and model
  of the pump. The pump strainer must
  be cleaned regularly, by monitoring
  suction pressure of the pump to
  ensure that the solids are removed
  as far as possible.
• A gradual reduction in the suction
  pressure of the pump indicates that
  the suction filter is getting choked
• Gaskets and O-rings of the pump to
  be renewed while overhauling.
• Check shaft bearing for damages
  and renew if necessary
• Check the condition of the
  mechanical seal especially the faces
  and O-rings. Discard the seal if face
  is damaged or O-rings hardened.
  Excessively leaking shaft seals
  should be changed without delay,
  as the leakage normally will grow
  worse and cause additional damage.
• Relief valve, valve seat, springs to
  be checked.
• Inspect for any scratches inside.
• LUBRICATION CHECKLubricate the motor and pump bearing
  as per manufacturer’s guidelines. It
  must not be over lubricated.
  Bearings damage occur due to over
  lubrication. The bearings must be
  lubricated in 6 months with high
  quality lubricant. Refer to the
  lubrication manual shared by the
  supplier
• ELECTRICAL ITEMS CHECKCheck motor amperage and relay
  settings.
• MECHANICAL SEAL- Mechanical
  seal may fail due to lack of
  lubrication and not following the
  quenching procedure. The
  temperature rises at the sealing faces
  that will damage the elastomer part
  of the mechanical seal.
• STATOR- If the pump is not to be
  used for 3 months or more, the stator
  (rubber elastomer) should be
  removed and kept separately in a
  clean, cool and dry environment It is important to note that most of the
  rubber products may change their
  physical properties under
  unfavourable conditions or if
  treated improperly, which will
  result in a shorter lifetime. They
  may also become useless through
  excessive hardening, aging,
  permanent deformation, cracking
  or other damages appearing to the
  surfaces.
• INTERNALS- Pump internals may
  rust if material of construction is not
  SS (Stainless steel). Anti-rust oil may
  be used on such parts.
• DRY RUN PROTECTION – Never
  run the pump dry as a few rotations
  in dry condition will damage the
  internal parts
• Storage of Screw Pump –
  If any pump is not to be installed
  immediately or the pump is not under
  operating condition for some time after
  being installed, the following points
  should be taken care of
• The pump should be kept in clean
  and moisture free area preferably
  with protective covering. If this
  cannot be ascertained, additional
  care should be taken to prevent rust
  formation.
• Pump should be kept after draining
  out the pumping fluid and
  preferably after flushing it from
  compatible fluid media. Anti-rusting
  oil or suitable agent must be applied
  on metallic parts and on those
  exterior, unpainted surfaces subject
  to corrosion.
• Ensure that the openings through
  suction and discharge ports are
  covered.

How to make Pumps More
Efficient

Major factors affecting pump efficiency
are throttled valves, pump over-sizing,
seal leakage and operational
breakdowncausing highest downtime
and cost. Therefore, it is important to
consider following points to make
pumps more efficient

• Usage of Variable Frequency Drives
  (VFD) – As the name suggests, VFD
  is used to achieve capacity at a given
  range of RPM rather than what the
  rated capacity of pump is. VFDs are
  used to limit unnecessary energy
  consumption and maintenance
  spares’ cost.
• Please connect a water flushing line.
• Connect a bypass.
• Since PCP is for viscous and
  abrasive fluids, do not switch the
  pumps frequently. Run the main
  pump (pump1) till maintenance is
  required and then switch to standby
  pump (pump2). Switch back to
  pump1 post maintenance. Periodic
  switching only to test standby pump
  can be done.
• Please refer to our previous article
  published in June 2021 issue for
  selection of pump as the model,
  curves, efficiency etc. depend upon
  capacity and pressure required.
• Email : headoffice@risansi.com
• Web. : www.risansi.com