What Do I Need To Control a Level or Set Alarms
Is there really end to the variations...we don't think so.
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Basic Level Control
Material: You need to select the probe materials. Usually the tank material is a good indication as to what the probe can be made from. PVC or plastics and stainless work well in water. Brass will blacken with water making it not the best choice. Hydrocarbons go good with brass. Floats should be selected to match the process as well. Our 316 stainless or our closed cell Buna works with most process product.
Connection: This is vast as well, basically if its out there - we can attach it to a level control. The most popular are fittings from 1/8" NPT to 2 1/2" NPT or ANSI flanges or brackets or we even can supply custom cut small flat flanges to fit old applications or industry standards. Remember to select a fitting that the float will go through. A 1/8" to 1/2" NPT probe is usually installed from inside the tank. We are working on a float to fit through a 1/2" NPT.
The Level: One switch point will usually cycle itself to death. You can get around this with very slow moving levels or a time delay on that switch. The best solution is a high and low. The points can be as close as 1/8" apart. So...you basically need a high and low to control a level.
Pump Control: In some applications a lag or backup pump is required to meet level demand or safety. The Almeg level control would then have four switch points to control two pumps. If one pump sits for extended periods, then an alternating relay is used. This device alternates pumps on every startup thus preventing one pump from seizing up due to lack of use.
Alarm: Many times with pump control, customers use Hi and
Hi Hi alarm at the critical end with a single alarm at the other.
For example the "Hi" would send an alarm while the "Hi - Hi"
may shut the system down. An alarm only level switch can
be used as well. A application may require, for example, six
switch points evenly spaced along the length of the probe.
They may all be in the normally open position for a tank filling.
As the process passed each switch point, the contact would
close indicating the level. Almeg builds small size level
switches ideal for cost effective single point high alarms.
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