DESCALING THE WATER OR STEAM SIDE OF HEAT TRANSFER EQUIPMENT
1. Check the water capacity of the tool or equipment to be descaled and calculate the amount of descaling
2. As a guide, for a tool of 20 litres water capacity, use two litres of descaling chemical (ie. a 10% solution by volume). A weaker solution may be used, but will take
longer to remove a given amount of scale.
3. For heat transfer equipment with water ways containing larger volumes of water, consider a descaling pump with larger pump
and pressure output.
1. Ensure an adequate water supply to dilute or neutralize any chemical leaks, or the spent descaling chemical, so that disposal does not contravene local regulations.
2. Isolate water inlet and outlet connections to the heat transfer equipment to be descaled, capping them off if necessary.
3. Couple flow and return hoses from descaling pump to the water inlet and outlet of the heat transfer equipment to be descaled to be
4. If it is anticipated that descaling is to be a routine maintenance procedure, consider installing valved tee-pieces in the standard flow and return connections
to the equipment to be descaled, terminating in 1/2” or 3/4” BSP male threads. This will enable immediate coupling of the descaling pump whenever
descaling is required.
5. The pump connection to the lower point of the equipment to be descaled should be through a valve, as a precaution. Failing this, if the descaling pump
is mounted below the equipment being descaled, power failure to the pump would result in the head of water in larger equipment being descaled overflowing the pump tank, unless prevented by closing the valve.
6. Connections should be made so that there is a closed circuit between the pump output hose, through the heat transfer equipment to the return hose.
7. Venting of the carbon dioxide gas evolved during descaling is achieved through the pump tank filler cap aperture. The cap should be screwed on by no more than
one quarter of a turn. This is sufficient to vent the gas, but at the same time reduces fumes and prevents splashes.
8. Connect the pump to a suitable earthed power supply. As the pump will be used in a damp location, a residual current circuit breaker plug should be used.
9. The flow reverser handle points in the direction of flow of the liquid. Turn the handle so that it initially points towards the hose going to the lower water
inlet connection. The hose from the top of the water outlet connection will then be the return to the pump tank.
10. Prior to adding descaling chemical to pump tank, first ‘prove’ the circuit with fresh water alone. Add water to pump tank to approx 10cm above minimum
liquid level, switch on pump, and Immediately open the valve detailed in point 5 above, to allow circulation to commence. If water level drops initially,
add more water to pump tank, and check that all connections are tight.
11. To commence descaling, slowly add descaling chemical into pump tank. Wait until liquid is returning into the descaling pump tank from the equipment being
descaled, and check to see if there is a build-up of foam on top of the liquid in the pump. If so, carefully add ScaleAwayDEFOAMER to the tank. This may happen when
there is a large amount of limescale in the equipment's waterways.
12. As circulation commences, bubbles and foaming will be seen in the return hose to the pump, indicating that limescale is being dissolved. If foam formation is
excessive, carefully remove descaling pump tank cap, and add ScaleAwayDEFOAMER to the descaling pump tank to stop the foaming.
SAFETY & HANDLING
13. Reverse the direction of flow periodically, checking all connections for tightness and absence of leaks.
14. Scale removal can be considered complete when bubbles are no longer seen in the return pipe, and yet the descaling solution is still sufficiently strong to
remove hard water deposits. ScaleAway's descaling chemicals contain a built-in colour change to monitor strength. An alternative simple check may be made by
dropping a sample of limescale into the solution, and observing if there is any effervescence.
15. For greater accuracy, a pH meter, or pH indicator paper, may be used to check the pH of the descaling solution. Once the pH has risen to 3.5 to 4, its ability
to dissolve limescale and corrosion deposits is effectively spent, and more descaling chemical or a fresh solution will be required.
16. After draining off the spent descaling chemical, flush the descaled equipment with fresh water. Many natural waters are slightly alkaline, and water flushing may be
all that is required. Alternatively, circulate a 1% solution of ScaleAwayNEUTRALISING-CRYSTALS through the tool for 15 minutes, drain, and then flush with clean water.
17. FWF ScaleAway System Descaling Carts C40 and C90 are available as FWF models. These have an integral fresh water
flushing facility. When descaling is complete, the spent descaling solution may be pumped to waste along the dump hose as follows:
18. If the flow reverser lever is to the left, twist the right-hand dump valve through 180 degrees to show the word ‘dump’, ensuring that the left-hand valve remains in
the ‘circulation’ position. (If the flow reverser lever is to the right, twist the left-hand dump valve through 180 degrees to show the word ‘dump’, ensuring that the
right-hand valve remains in the ‘circulation’ position.)
19. When ‘dumping’, the water level in the pump tank will fall by the same volume as is being dumped. Open the mains water supply valve and adjust to allow fresh
water to enter the tank at the same rate as water is exiting the dump hose. Make sure that the tank water level remains at least 10 cm (4”) above the minimum mark.
Continue dumping until fresh water is leaving the end of the dump hose.
20. Turn the valve which is in ‘dump’ mode through 180 degrees to restore full circulation through the pump and the system. Close the water supply inlet valve once
the level in the reservoir has stabilized between minimum and maximum markers. Allow fresh water to circulate through the pump and the system. Close the water supply
inlet valve once the level in the reservoir has stabilized between minimum and maximum markers. Allow fresh water to circulate through the descaled equipment
for ten minutes.
21. Operators may prefer to neutralize the spent Descaling solution “in situ” whilst the liquid is still circulating, by carefully adding Neutralizing Crystals
or Neutralizing Liquid to the solution until the pH is brought up to a value of 7, and then flushing to drain. When using Neutralizing Crystals, if foaming is
excessive, carefully add a little ScaleAwayFOAM BREAKER to the descaling pump tank.
When working with acidic descaling chemicals, always wear suitable protective clothing and goggles. Refer to instructions on labels of descaling chemicals, and refer
to Material Safety Data Sheets. Caps should be kept securely on all chemical containers whilst not in use. To avoid splashes, operators should not stand directly
over the open neck of either chemical containers or the filling neck of the descaling pump whilst pouring or adding chemicals.
NB. When descaling with any acid, there is the possibility of hydrogen being evolved. Hydrogen is a flammable gas, and the working area should be well ventilated.
Avoid smoking nearby, or any other means of ignition.
It is stressed that these are guidance notes only, and the above information is based on the present state of our knowledge of heat transfer equipment in general.
It is given in good faith, but due to the diverse and varied nature of such equipment, the user must satisfy himself that the above procedure is viable in the
Why Use ScaleAway’s System Descaling Carts?
Maintaining your heat transfer equipment is not just a good idea, it is a requirement for any winning business
strategy concerned with sustained manufacturing productivity etc.
- Your equipment will be cleaned in only hours without disassembling any part of the equipment.
- Equipment can also be cleaned without any down-time (cleaning on the run).
- Cleans down to the original surface without pitting.
- Removing the scale build-up allows your equipment to operate more efficiently with less down-time.
- Using ScaleAway's descaling chemicals will extend the usable life of your equipment, especially when used as a part of a
regularly scheduled preventative maintenance program.
- ScaleAway's range of descaling chemicals are safe on copper, copper-nickel, bronze, brass, iron, mild steel, stainless steel cast iron, aluminium and
zinc galvanized equipment - Refer to our product list for appropriate descaling chemical for your specific application!.
Contact us TODAY to purchase these System Descaling Carts so that your in-house maintenance team can descale your heat transfer equipment as often as you see fit,
enabling maximum heat transfer efficiency at all times!