Nortec DRAABE Pure Water System - Manual (Page 24)

Created: 21.09.2006
Changed: 29.02.2008
Printed: 02.03.2009
page 24 of 59
4.1.2 Pure Water System with Water Softener Type SoftCab (Air Humidification and Process Water)
EXAMPLE 2
A DRAABE Pure Water System is to be installed in the paper warehouse of a printing plant
for air humidification and for process water. The following data are known:
humidification rate:
57 kg/h (126 lbs/h).
process water rate: 40 kg/h (89 lbs/h).
humidifier type: unitary nozzles, DRAABE TurboFog
raw water:
hardness = 16°dH
conductance = 400µS
With a total rate of 97 kg/h (215 lbs/h) for humidification water and process water one
needs a 120 litre system. A PerPur 120 is selected.
In our Example 2 we use a SoftCab 25 DR. This has a capacity of 90,000 litres for 1°dH
The required output rates are doubled because of the waste water for reverse osmosis and
the raw water hardness of 16°dH is increased by a safety term of 5°dH.
total pure water rate:
240 litres/h (530 lbs/h) ((= 2 x 120 litres))
capacity of softener: 90000 litres / (16°dH + 5°dH) = 4200 litres
time before regeneration: 4200 litres / 240 litres/h = 17h
SOLUTION TO EXAMPLE 2
According to the foregoing example the resins must be regenerated after ~ 17 hours.
IMPORTANT: During the periods of regeneration (approx. 2 hours) no treated water is
available for air humidification.
For questions about computation of humidification rates please contact DRAABE Ottawa.
4.1.3 Pure Water System with Water Softener of Type WSD
Systems with double softener (WSD) use two resin cartridges. When one of them is being
regenerated the other is producing softened water. The result is a continuous, uninterrupted
supply of treated water.