Trickle valves are low in first cost, have zero operating cost, are easy to install, have no electrical connection, easy to inspect even while in operation, and last a very long time.
Here is How They Work
1.The trickle valve must be under suction; the fan on the downstream (clean air) side of the dustcollector.
2. A high efficiency (long cone) cyclone with the fan on the upstream (dirty air) side may create sufficient suction at the dust discharge to permit use of a trickle valve.
3. In any case, a head of material will build up above the trickle valve equal to the suction in the cone or hopper above. Example: If there is 10" water gauge suction at the trickle valve and the collected material has a bulk density of 31.2 pounds per cubic foot (1/2 of water), then material will build 20" above the trickle valve.
4. If this build of material above the valve is not desirable, such as in the cone of a cyclone or upabove a safe point in the hopper of a bag collector, then a spool piece should be used above the trickle valve.
5.The length of the spool piece is determined by multiplying the inches water gauge suction by 62.4 (water density in pounds per cubic foot) and dividing by the collected material bulk density in pounds per cubic foot. Some engineers like to add 30-50% more to compensate for aerated material, which may have an actual bulk density much lower than that computed from material at rest.
6. On start up of the dust collector, the trickle valve will not discharge until a head of material is established. When it is established, a trickle of material will start flowing at the same rate it is being collected above. Upon shut down, the trickle valve will discharge all of the head of material, thus leaving the dust collector hopper nearly clear of all dust.
7. Pulse jet bag dust collectors will cause a trickle valve to "puff," thus causing a secondary dust problem at the dust discharge. This is overcome by connecting the outlet of the trickle valve directly to the receiving vessel or draping between the two with a cloth sleeve.
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See also our Frequently Asked Questions.
Since 1921, Industrial Dust Control, Ventilation and Process Equipment
& Hiester, Inc.
P.O. Box 1885
Saginaw, MI 48605-1885
Local and International - 989-792-3443 or 989-793-2420
Toll Free - 800 332-4031
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