Carpet/Rug/Upholstery Cleaning / Truckmount Equipment / Accessories

Pumps 101: An A-to-Z Guide on the Heart of the Truckmount

January 30, 2014

Pumps are the heart of the truckmount, yet are somewhat of the unsung hero when it comes to making a truckmount tick. Here’s a look at everything from high pressure (HP) to chemical pumps to how to maintain this critical piece of the truckmount pie:

High Pressure (HP) pumps

These pumps produce the high pressure water (100 to 3000 PSI) needed to deep clean any carpet or hard surface.

  • Pump pressure (PSI) and flow rate (GPM) are rated by the pump manufacturer, however the actual output of your pump will be impacted by the controls and components installed on your truckmount or portable carpet cleaning machine, as well as conditions specific to you.
  • Engine rpm: HP pumps produce the best water pressure/flow rate at specific rpm’s. Truckmount manufacturer’s select and install pumps based on application as well as engine size and rpm. It’s important to use the same pump or a pump with the same specifications when a pump change out is required.
  • Pressure regulator/unloader: Adjusting the regulator/unloader has a major effect on water pressure and flow. Because of connected component requirements i.e. heat exchanger psi specifications etc., the regulators/unloaders in most cases are specific to truckmount models, to prevent improper performance and potential damage to connected components use the same regulator/unloader when change out is needed.
  • Clogged, damaged, or leaking components: Hard water scale buildup – can cause water pressure, water flow and water temperature loses of 75% or more. A properly maintenance water softener is the #1 solution in reducing scale build up, the second option is to perform regular system descales – descaling is a service best left to professional service technicians.
  • Leaking or damaged hoses, tubing, valves, fittings etc. are major factors in flow rate and pressure.
  • Clogged inline filters and screens are another major factor of flow rate and pressure. Clean screens and filters regularly and replace them when needed.
  • Spray jets used: The number of jets and the jets orifice sizes effect water pressure and flow. It’s best to replace worn out jets with jets having the same GPM rating and spray pattern the manufacturer originally used.
  • Inline components such as heat exchangers: Tubing diameter and tubing length within the heat exchanger(s) effect water flow and pressure.
  • Hoses and fittings: The length and diameter of hoses/tubes and fittings which water must pass through effect pressure/flow.
  • Incoming water volume (water supply): The pump’s output (GPM) flow rate can only be as high as the incoming water flow (GPM).
  • Incoming water temperature: High Pressure pumps have an incoming water temperature limit that must not be exceeded, the temperature limit varies by manufacturer and pump model, water feeding into the HP water pump at too high of a temperature will cause reduced pressure as well as the potential for damage to pump seals and O-rings.
  • Chemicals: Running cleaning chemicals through the pump is NEVER recommended. Cleaning chemicals will deteriorate pump seals and O-rings and can cause cavitation (air pockets) which create pump overheating and damage.
  • Condition and age: The age and condition of the pump, hoses, valves and jets etc. effect pressure and flow.

Chemical pumps:

These automatically dispense metered amounts of chemicals into the outgoing high pressure water – just set it and clean!

  • Last Step Injection Chemical Systems: A small pump is attached to one of the HP pump ports, the pressure created by the HP pump port causes a rubber diaphragm inside the chemical pump to move back and forth creating suction which pulls chemical out of the chemical jug, a metered amount of chemical is fed into the water flow as it exits the truckmount and heads into the solution hose to the wand or tool.
  • The chemical pump rubber diaphragm mentioned above can handle up to 400 psi, setting the water pressure above that will cause premature wear and damage.
  • Chemical pumps require minimal maintenance, the rubber diaphragms are constantly stretching which causes wear. These diaphragms will require replacement on a regular basis, the chemical pump’s check valves and O-rings  will need to be checked regularly to ensure proper function and that no leaks are present.
  • Siphon Chemical Systems: Chemical is drawn into the outgoing water through an inline check valve which reduces the outgoing water pressure by 60 to 100 psi, the psi reduction creates a vortex which siphons a metered amount of chemical into the water flow as it exits the truckmount and heads into the solution hose to the wand or tool.

Demand pumps:

These are used with onboard fresh water supply tanks – makes the cleaning vehicle “self-contained”:

  • Small 12v pumps come in many varieties and are produced by several different manufacturers.
  • Most of these pumps are not built to hold up under the constant on and off cycling required in normal cleaning. Pumps look similar but don’t be fooled, pick the wrong pump and you’ll be replacing a motor or pump head or buying another pump in just a few months.  We strongly recommend a demand pump system which incorporates an accumulator (bladder tank). The bladder inside the accumulator is filled with air, water from the demand pump fills the accumulator, when your machine needs more water the water box float opens allowing the air pressure in the bladder to push the stored water from the accumulator to the machine which significantly reducing the cycling of the pump.

Auto Waste Pump-Out Pumps (APO):

These are used to automatically pump waste water and debris into a toilet or sink, straight into the sewer system:

  • These are heavy duty pumps built to remove cleaning and restoration waste water and debris by automatically pumping it out of the truckmount waste tank through a hose directly into a toilet, sink or approved sewer drain.
  • Value: With a properly functioning auto waste pump-out your truckmount’s waste tank will never overfill or even get to the point of tripping the waste tank full float and shutting down your machine. You’ll never have to haul around a waste tank full of stinky, putrid, nasty waste water. You won’t be required to find a separate approved dump site that requires travel to and from, and you won’t get caught dumping the slim onto your customer’s lawn, driveway or parking lot.
  • It’s important to keep it clean, the debris in waste water will build up on the internal parts over time which if not cleaned can cause damage to the internal diaphragms and O-rings.
  • When these pumps are properly cared for, you simply run the hose to a toilet or sink and turn the pump on – it does the rest, it’s a beautiful thing!

Pump Maintenance – Upkeep:

  • Pumps as with any mechanical equipment when properly maintained will perform well and provide dependable service for many years, or, when poorly maintained will be very expensive and die young. The owner/operator must be OBSERVANT – look, listen and inspect.
  • Closely follow the manufacturer recommendations for daily/weekly/monthly maintenance, check oil  levels, inspect filter, hoses and belts, pay close attention and correct any loose bolts or wiring that looks damaged, listen for new or unusual sounds, watch for and inspect unusual sights or smells and take corrective action immediately. Take care of little issues before your valuable equipment gets to or beyond the breaking point.
  • High Pressure Pumps and Auto Waste Pump-Out upkeep involves lubrication – (pump oil changes) and the periodic replacement of O-rings, seals, check valves and drive belts. These are all part of normal maintenance. Demand pumps may require occasional replacement of check valves or the pressure switch, and proper installation and wiring is important with these pumps.  

Freeze Protecting Pumps:

  • Never allow pumps with water in them to reach freezing temperatures
  • Frozen water in pumps exerts pressures of 90,000 lbs-per-in², damaging forces that can make pump repair and replacement necessary
  • Two recommended options for freeze protection are antifreeze and store equipment inside a heated building or garage

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