Many types of filter nozzles in our product portfolio can be used in open gravity filters with extended stem versions. These products include long stem nozzles, sleeves for concrete or steel plates, protection caps or covers, fixation nuts or bolts. The sleeves are prepared and located prior to concrete casting in place, or the concrete plates can be prepared in advance as precast. Finally, the filter nozzles are placed inside the sleeves.
Some important criteria for choosing the correct filter nozzles for open gravity filters can be mentioned as follows:
* flow rates (during service and backwash operation)
* calculating correct number of filter nozzles, their general layouts in order not to have ineffective zones in the bottom of the open gravity filter
* choosing the correct design filter nozzle
* the adequate stem length and air holes on the stem for proper filtering 
* sufficient air cushion volume 
* proper filter nozzle design to help stopping possible micro-organisms and bacteria growths
* user-friendly filter nozzle by the help of handy tools for mantling and dismantling
* the thread direction of the filter nozzles should be opposite to tightening direction
Sleeve lengths    : plates from 60 mm to 500 mm (please contact us if sleeve length requested is longer than 500 mm)
Sleeve threads    : 7/8'' -  15/16''W - 1'', M24 - 1/2''G - 3/4''G - 1''W - 1¼''W
Slot openings      : 0.15 - 0.20 - 0.25 - 0.30 - 0.35 - 0.50 - 0.60 ..... mm
Filter nozzels       : Many options from our product portfolio 
Accessories        : Fixing bolts, nuts and caps for sleeves
            AIR BACKWASH                          WATER BACKWASH                              FILTER NOZZLES ON CONCRETE PLATES
                             G                                                            GM                                                         GE
                      G - SPECIAL
                      M - PIPE