Multiple Point, Top Mounted Level Switches
|LS-85 / LS-86 Liquid Level Switch
The LS-85 ( multiple float), and LS-86 (single float) switches are designed to be inserted into a nozzle that is located at the top of a process vessel.
Construction consists of a stainless steel guide tube containing a hermetically sealed reed switch , or switches, with a welded plug at the lower end. Near the upper end , the guide tube passes through, and is welded to a flange or threaded pressure fitting. This fitting is sized to match the existing process vessel fitting. A stainless steel float that is constructed with hollow guide sleeve through it's center, and containing a magnet is assembled to the guide tube. The float follows the liquid level and in turn activates the switches that are located at desired trip points inside the guide tube. The electrical switch wiring is routed out of the top end of the guide tube, and into a top mounted electrical termination housing.
These devices can be equipped with from 1 to 4 trip points, flying lead or terminal type field wiring connections, latching or current amplifying relays, single or multiple floats, SPST and SPDT reed switches, and in many materials, custom lengths, and other options.
A frequent use for the LS-86 switch is to control a waste water sump pump. An LS-86 is installed into the sump, equipped with a single float, and with 2 reed switches for high level and low level trip points. A latching relay is installed in the top terminal housing , and it's contacts are wired to directly control the sump pump. When the sump level reaches the high level trip point, the relay energizes and starts the sump pump. The relay remains energized, and the pump starts. The pump runs, and the sump level drops until the level reaches the low level trip point. At this time the relay de-energizes and the pump stops. The cycle repeats as the sump refills, thus providing a cost effective, local sump control solution !
LM-90 Liquid Level Switch
The LM-90 Switch is designed to be flange mounted or may be fitted with a threaded mounting to be inserted into a top tank located nozzle. It may also be mounted into a bridle chamber external to the process vessel, or into an existing stilling well that is installed in the process vessel.
A float with attached rod and magnet follows the liquid level. An ES-30 or ES-40 Electric Switch mounted to the outside of the magnet guide tube is actuated magnetically when the magnet passes the switch. The switch trip position may be easily moved by loosening the clamp mounting, then sliding the switch to it's new position. Multiple switches can be mounted to provide different switch points, or adjacent to each other to provide multiple isolated switch poles.
The main advantages of the LM-90 over other liquid level switch configurations are the ease of adjustment to trip positions, high pressure capabilities, and the isolation of the switches from a high temperature process.
PROMAG can supply these switches in many materials, configurations, and lengths, and mountings. The AS-35, and AS-50 pneumatic switches may be used to provide pneumatic rather than electrical outputs. External bridle chambers, and internal stilling wells are available to suit your custom application.