Documentation:

Brochure

Purain DN 150-S Spec Sheet

ACCESSORIES

6" pipe connection kit

Backflushing nozzle

Calming inlet

Low rainfalls

Low rain­fall events ac­count for over 97 % of total an­nual rain­fall. There­fore, it is par­tic­u­larly im­por­tant that the fil­ter be de­signed to col­lect this light rain­fall. While many fil­ters are not de­signed to col­lect light falls, the rain­wa­ter col­lected in the hy­draulic jump fil­ter tray is then fil­tered and drained into the tank. The tray en­sures that no pre­cious water is lost.

High Rainfalls

High rain­fall events, that occur ap­prox. 4 to 10 times in a year, con­tribute only about 3% to total water yield and are used by the PU­RAIN Rain­wa­ter fil­ter for self-clean­ing. These high rain­falls lead to the for­ma­tion of an eddy in the PU­RAIN rain­wa­ter fil­ter, the so called hy­draulic jump, which spins with such great force that even dirt ac­cu­mu­lated in the tray is flushed and dis­charged with the over­flow.

The PU­RAIN Rain­wa­ter fil­ter cleans it­self dur­ing heavy rain­fall events. It means min­i­mum main­te­nance costs for the user in com­par­i­son to other fil­ter sys­tems.  An over­all rain­wa­ter fil­ter­ing ef­fi­ciency of 98 % is achieved with the unique, self-clean­ing PU­RAIN Rain­wa­ter fil­ter.  
With the hy­draulic jump fil­ter, this water is col­lected in a tray, which is then fil­tered and drained into the tank. The tray en­sures that no pre­cious water is lost. 7.7 lbs of sand-gravel mix­ture was flushed away in just 30 sec­onds dur­ing this trial (see photo) due to the ef­fi­ciency of the hy­draulic jump.

PURAIN 150 in a commercial application 

Where can I in­stall the PU­RAIN rain­wa­ter fil­ter?

The IN­TEWA PU­RAIN fil­ters can be eas­ily in­stalled in most stan­dard tanks of  plas­tic, con­crete, in­door and out­door con­struc­tion. Many dis­trib­u­tors de­liver your stor­age tank al­ready fit­ted with a PU­RAIN fil­ter. The PU­RAIN Fil­ter is also suit­able for in­stal­la­tion out­side the tank if re­quired. HD Fil­ters are de­signed for di­rect sub­sur­face in­stal­la­tion. While in­stalling the PU­RAIN fil­ter, make sure that a lower height off­set is pre­sent be­tween the in­flow and the out­flow.

Is there a fil­ter with­out height off­set be­tween in­flow and out­flow?

The PU­RAIN rain­wa­ter fil­ter works with the min­i­mum pos­si­ble height off­set be­tween the in­flow and out­flow. A height off­set is a pre­req­ui­site for a self-clean­ing fil­ter in order to en­sure proper op­er­a­tion. Since 1993, IN­TEWA has ac­cu­mu­lated a lot of ex­pe­ri­ence test­ing dif­fer­ent types of self-clean­ing fil­ters – none of which, func­tion with a high de­gree of ef­fi­ciency. Al­ter­na­tively, only a col­lec­tion fil­ter may be used in place of a hy­draulic jump, how­ever they have to be cleaned reg­u­larly and do not guar­an­tee the best qual­ity water fil­ter­ing.  

Is the rain­wa­ter fil­tered by PU­RAIN well suited for wash­ing ma­chines?

The water fil­tered by the hy­draulic jump fil­ter is per­fectly suited for use in toi­lets, wash­ing ma­chines etc. It should be noted that the qual­ity of water also de­pends on the stor­age of the rain­wa­ter. Fac­tors, such as tem­per­a­ture of the stor­age tank, in­flow calmer, over­flow skim­mer,  size of tank, etc. are crit­i­cal for an op­ti­mum qual­ity of water.

Does self clean­ing = main­te­nance free?

The PU­RAIN-fil­ter is ex­tremely low main­te­nance. Dirt and leaves in the sed­i­men­ta­tion cham­ber do not need to be re­moved be­cause they will be flushed away with the next heavy rain­fall. If the sieve does be­come clogged, it is eas­ily cleaned through the tank lid with a high pres­sure cleaner. Al­ter­na­tively, in rare cases, the sieve can be re­moved for clean­ing. Should a fil­ter be mounted in a hard to ac­cess place, it can also be cleaned via the in­stal­la­tion  of a back­flush­ing noz­zle. This is avail­able as a PU­RAIN ac­ces­sory. We rec­om­mend that you check your fil­ter about sieve twice a year.

How is the ef­fi­ciency in other con­di­tions of rain?

The over­all ef­fi­ciency of the PU­RAIN rain water fil­ter is rated at 98 %. Hereby, the small to medium rain­falls are col­lected 100 %, but the heavy rains (which ac­count for only about 3 % of an­nual rain­fall yield), are uti­lized for the self-clean­ing func­tion of the hy­draulic jump fil­ter. Even in areas which ex­pe­ri­ence more heavy rain­falls the ef­fi­ciency of the PU­RAIN fil­ter is well over 95 %.

How do I in­stall the non-re­turn valve and over­flow skim­mer used with the big­ger PU­RAIN rain­wa­ter fil­ters?

The non-re­turn valve and over­flow skim­mer, made from moulded parts, are sep­a­rately in­stalled in the tank.