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Hall Effect TwinSite® for LP Gas Service


The TwinSite® is a magnetically-driven, Hall Effect, voltage output sender. Senders are utilized on stationary applications where direct reading plus an electrical signal to a remote fuel level monitor are required. Models are available to fit all Rochester Junior, Senior and Snap-On.

General Information & Features

In the area of LP gas measurement, a magnetic drive feature is important because the fluid is stored under pressure. A magnetic drive allows a signal from the float mechanism inside the tank to be transmitted through a solid, non-magnetic bulkhead without the necessity of dynamic seals or pressure-type conductors.

Previous designs of liquid level gauges for magnetically driven dials which produce an electrical output signal had the disadvantages inherent in using variable resistors with a wiper arm contact. There has been a need for a more reliable and simplified design for LP liquid-level gauges which would provide an electrical output related to the liquid level in the vessel.

Hall effect is a solid state technology with no moving contacts. It counts on the fact that a magnet bends the path of electrons moving through a semiconductor. The bending of the electron path can be detected and converted into ratiometric voltage output.

Hall effect sensors have been employed in various automotive applications such as for detecting throttle position. The magnetic connection of the Hall effect sensor is more reliable than systems that depend on the sliding contact of variable resistor devices.

Many existing home and small business LPG storage tanks are equipped with gauges with weak drive magnets suited for low friction direct-indicating dial assemblies. There is no sliding wiper contact, and is compatible with existing gauges equipped with weak drive magnets within the tank. The Hall Effect Twinsite® is advantageous in that it can be used as a retrofit on these vessels to provide an electrical output which can be utilized for remote monitoring of tank levels. With remote monitoring of tank levels, distributors of LP gas will be able to more efficiently plan deliveries to various consumers.

The TwinSite® also provides the easiest to read local indication of any TwinSite® sender Rochester has produced. The bright, user friendly dial face is divided into percentage units.

The case is hermetically sealed by ultrasonic welding to melt and fuse the case into one solid piece. This keeps weather out, ensuring “no-fog” readability while greatly extending mechanical life. This Ultra Sonic weld process is highly reliable and features a back-up o-ring seal. The plastic case is capable of withstanding vibration and shock that would render comparable metal designs useless.

The plastic case is far more resistant to corrosion than any metal-cased version and is capable of withstanding broad variations in temperature. The plastic lens (and the rest of the case) is a special, UV stabilized material.

Electrical connections are sealed with redundant epoxy chambers. The connecting wires are also sealed behind this epoxy barrier. This sealing process presents an impervious barrier to water.

The sender is mounted onto the Rochester Junior gauge with #0040-00416 stainless steel dial screws (6 — 32 x 3⁄8"). An additional item available to ensure weatherproof connections from the TwinSite® to the receiver is heat shrink solder sleeves part number 0025-00495.


Data Sheet

DS-1318 application notes

WD-566 Control Drawing (available upon request)

General Specifications*

Operating Temperature

-40°F to 176°F, -40°C to 80°C.


±1-1/2% at E, ±2% at 20%, and ±3 at higher graduations. (Float gauge errors not included.) See DS-1318.


Less than 1% typical.



Opp. Range

4.5 to 5.5 vdc/ratiometric.
Can be made compliant with alternative operating voltages.

Output Voltage with 5.0 Volt Input

Ratiometric 8-80% of input voltage @ 8-80% volume.
Ratiometric: Empty is 0.4 volt or 8% of input voltage.
Full is 4.0 volt or 80% of input voltage.



Hall Effect Twinsites® are UL Classified as intrinsically safe for Class 1, Division 1, Groups C & D (Hazardous Locations).


When Ordering Specify:

1. Junior or Senior or Snap-on.

2. Or part number.


*Materials and specifications are subject to change without notice. Pressure ratings subject to change due to temperature and other environmental considerations.

WARNING! This sensor is not to be used as the primary means of determining high or low fuel condition. It must not be used in the absence of redundant systems in critical applications where there may be significant safety risk or financial exposure in the event of fuel overfill or fuel exhaustion condition. This sensor is not to be used for tank filling.

Materials of Construction*

Crystal & Case

Polycarbonate, ultrasonicaly sealed.


Painted aluminum.


How to Order**

Hall Effect Twinsite® Series

Part Number Style Circut Wires
5901s02713 Jr. Ratiometric None
5950s02713 Sr.
5994s02713 Snap-on

Potting Cap

Part # Description
0023-00502 Potting cap for Hall Effect Twinsites

Hall effect components only available through remote monitor OEM's.

**NOTE: These parts numbers are furnished less wires.