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Water treatment
The water used in air handling units equipped with washers or humidifiers must be treated to prevent both corrosion and scaling.
The balance of the water used in our washers and humidifiers is altered by the spraying and evaporation processes. As a result, it contains dissolved salts and carbon
dioxide, both of which cause fluctuations in the hardness and pH of the recirculated water.
This shows that the problem is extremely complex and that great thought must be given to selecting a water treatment system (scale inhibiting or water softening equipment).
We recommend contacting specialist firms.
Blowdown valve
In addition to water treatment, continuous blowdown is necessary in order to limit the concentration of dissolved salts.
The flow rate of this blowdown blowdown is a case in point and depends primarily on water quality.
That is why we recommend, 3 to 4 weeks after commissioning, testing the pH of the water in the collection tank and adjusting the flow rate of the blowdown valve as
necessary.
BLOWDOWN VALVE FLOW RATES
For guidance:
•
If the water is treated by injecting a silicate, the blowdown flow rate must be equal to the flow rate of the evaporated water.
•
In the case of sodium-rich permuted water treated by injecting a silicate, the blowdown flow must be equal to one-third the flow rate of the evaporated water.
•
In the case of water that has been deionised using scale inhibitors, the blowdown flow rate must be equal to one-tenth the flow rate of the evaporated water.
•
In the case of normal water, (pH 7) and an average < water hardness< (7 <\\> °f > 15), the blowdown flow rate must be amount to between 1% and 5% of the flow rate of
the recirculated water (humidifier).
3. MAINTAINING THE EVAPORATIVE HUMIDIFIER
Maintenance
Regular maintenance is the key to ensuring your humidifier operates satisfactorily.
Maintenance frequency largely depends on evaporation rates, dust contained in the air, water quality and whether the water used is recirculated or renewed.
Check the humidifier four times a year and clean it at least twice a year.
When inspecting the humidifier, check the following:
Special operating conditions
If humidification is shut down for a certain period of time, the tank must be drained of water and cleaned.
In the case of extended shutdowns, remove the modules and store them in a sheltered location.
If the humidifier is exposed to water containing high levels of calcium and bicarbonate, or to dust-laden air, allow for more frequent inspections.
If recycled water is used, the blowdown flow can be increased. These actions will depend on each case and can be determined by testing.
Precautions to be taken before commencing major work
Shut down the pump or close the supply valve and allow the fan to run for about 30 minutes in order to dry out the humidifier.
The module is relatively fragile when damp and must be handled with care.
1. Both sides of the humidification surfaces must be damp.
If this is not the case, then check the distribution system
included with the module.
2. The blowdown valve should be delivering a flow of water.
If it is not, clean the valve and readjust the flow rate.
If deionised water is used, the lower flow rate may cause
accelerated clogging of the valve.
3. The humidification module and the tank should be clean.
4. The P-trap should be filled with water.
5. That the front and rear surfaces of the humidifier should be
free of deposits.
If deposits are found, raise the blowdown flow rate by 25%.
