MODEL 4.

These filters are used to produce a representative and clean sample from liquid samples. They are not suitable for flue gas or other gaseous samples and will also have problems with high proportions of multi phase gas/liquid samples.

However, they are ideal for the removal of sludge and granular solids in waste water and process samples, [See also Backfush Model 8800]. The self cleaning action of these filters is different from the Model I or II filters.

The sample is pumped or piped under its own pressure into the filter. Inside the filter body is an annular space and a formed orifice set a small distance from the filter element. The sample impinges on the filter element and the high velocity, distance and shape of the orifice cause the filtrate to pass through the filter element and the solids to be carried away in the by-pass flow.

Applications are mainly in the Waste Water and Chemical Effluent Sampling.

The main applications for simple model IV filters are in filtering high granular solids from liquids. It is possible in some circumstances to obtain continuous filtrate from a 40% laden aqueous sample. However, viscosity and nature of the fluid and solids must be considered in any application.

These filters have considerable use with pH and conductivity systems as well as many ingenious situations. Opportunities exist at all times it is recognising them as a potential solution that may be difficult.

Filter elements are available from 5 to 100µ in a variety of materials such as polypropylene, AISI-316 and -304 stainless steels. [For exact mesh sizes and support requirements consult your local representative].

Filter body materials are available in Polypropylene or P.V.C. [Standard], AISI-316 stainless steel and also from PTFE or Kynar [PVDF]. The latter are used for highly corrosive liquids, e.g. Hydrochloric Acid.

The Model IV filter has a diameter of 75mm and a height of 90mm. The sample by-pass inlet and outlets sizes are 1/2" NPT i. The sample filtrate outlet is 1/8" NPT i.