Frequently Asked Questions Float Switches

Contegra Inc Eagan, MN 651-905-0900

Table of Contents

1. What switch the switch rating of the FS 96 Mercury float switch?
2. What switch is used inside the FS 90 Non-mercury float switch?
3. How does the FS 90 Laminex™ coating compare to that used by other companies?
4. How can I protect the FS 90 or FS 202 reed switch?
5. What are the FS 202 contact ratings, certifications and installation instructions?
6. FS 202 product update.

Back (FAQs)

What is the switch rating of the FS 96 Mercury float switch?

Each FS 96 uses two small SPST mercury switches to create a NO (normally open) and NC (normally closed) contact, allowing the ordering of a single float to create a SPDT reed switch.  The switch ratings are:

What switch is used inside the FS 90 Non-mercury float switch?

Effective 7/02.

Reed switches should be protected if they are switching inductive loads.  Reference the section (below) which covers "How can I protect the FS 90 or FS 202 reed switch?"

How does the FS 90 Laminex™ coating compare to that used by other companies?

US Filter/Control Systems uses a Teflon® formulation called Silverstone® (both trademarks of Dupont).  The two advantages of Teflon are 1) it is chemically inert, and 2) when used in cooking applications the Silverstone® stains less than Laminex™ (reference www.silverstone.com for further information on Silverstone's® cooking applications.).  The Laminex™ epoxy coating is also chemically resistant and has shown a superior ability to shed materials fast.

Click here for a picture showing a Contegra Laminex™ coated float switch shedding solids faster and a Silverstone® coated float switch.

How can I protect the FS 90 or FS 202 reed switch?

Reed switch contact ratings, as listed in the FS 90 or FS 202 data chart, are based on use with a resistive type load. For applications requiring the control of an inductive or capacitive load, additional interface circuitry may be required.

When the current is interrupted, the inductance of the load generates a voltage which appears across the switch contact. If the voltage is large enough, it can cause arcing. Arcing can cause the contacts to weld to each other resulting in unreliable switching performance. It is essential to protect the circuit by suppressing the voltage to prevent arcing. This can be accomplished through the use of a diode for DC circuits (figure 1) and a resistor-capacitor network or Quencharc for AC circuits (figure 2).

What are the FS 202 contact ratings, certifications and installation instructions?

UL Recognized

Contact Ratings: 0.2 A @ 120 VAC, 0.5 A @ 24 VDC

For Haz. Locations Class I, Groups A,B,C,D; Class II, Groups E,F,G, Class III

1. Install rigidly & vertically
2. Do not exceed temperature limits of PVC.
3. Assure liquids are chemically compatible with the switch and mounting hardware:  Buna N, PBT, and PVC
4. Ambient temperature changes affect switch setpoints.
5. Minimize shock and vibration.
6. Use in clear liquids. (Low turbulence increases life.).
7. Apply within switch ratings.

FS 202 product update.

The junction box of the FS 202 has been changed.  There are now only two mounting holes.

The sales literature is being modified and will be posted when completed.

Copyright © 2001  Contegra Inc.   All rights reserved.
Revised: July 14, 2005.