How-to: Choose a Float Switch and Counterweight

Last updated: 2 Apr 2025

Our FLO Series of float switches consists of five different level sensors that provide automatic level control and monitoring for various specialist applications, from diesel fuels and explosive atmospheres to drinking water and waste management.

Complementing the FLO Series are our four float switch counterweights that perform one of two functions:
Stabilising weights to act as a pivot point in tanks or wet wells that have no fixed objects to attach a float to,

Weights that can be attached to any point of a float switch to adjust its differential switching point (high or low level) based on your level control needs. With five float switches and four counterweights, which float and weight combination do you need for your application?

Selecting a Float Switch

FLO Series level sensors are non-mercury and instead operate via an internal microswitch and rolling ball operator housed in a polypropylene case. Each unit has individual features that ensure long-term monitoring and control in their intended application:

FLO101 – ATEX Rated Zone 0 Float Switch

The FLO101 has a special low-voltage switch that is ATEX and IECEx approved for safe use in Zone 0 applications – the most hazardous zone where explosive gasses, vapours and mists are present.

FLO102 – General Purpose Float Switch

FLO102 is designed to provide reliable level control and monitoring in non-specialist settings, such as filling and emptying pumping station chambers. The main body of the polypropylene float switch can withstand up to 10bar of pressure, with a rated continuous pressure rating of 5bar.

FLO103 – Economy Float Switch

A lower cost alternative to the FLO102, the FLO103 provides the same reliable level control in non-specialist applications.

FLO106 – Fuel Float Switch

The FLO106 is made for use in diesel and fuel oil applications – it’s cable is sheathed in oil-resistant polyurethane which is suitable for use in damp and wet environments.

FLO106 fuel and diesel oil float switch.

FL107 – Potable Water Float Switch

FLO107 has been independently certified as suitable for installation into potable water, holding both WRAS (Water Regulations Approval Scheme) and NSF (National Sanitation Foundation) REG4 approval that guarantees compliance with UK drinking water laws.

FLO107 potable/drinking water float switch.

Selecting a Counterweight

Although all our float switches perform the same duty, each one is specially designed for long-term and accurate level control in different applications:

FLOCW-1

FLOCW-1 is a polypropylene body filled with granules that provide its weight. This counterweight is mounted by passing the cable through its body and must be secured externally (e.g. cable tie) to maintain its position.

FLOCW-2

Like the FLOCW-1, the FLOCW-2 counterweight is attached by threading the cable through the body. However, the FLOCW-2 does not need affixing externally as it features an inbuilt stuffing gland that secures the location of the counterweight on the cable.

FLOCW-3

The FLOCW-3 is weighted by a solid disc of material encapsulated in polypropylene. Although the weight can be secured by threading the cable through the supplied cable apertures, it can also be attached to the float switch cable by using a cable tie to fix its position. This makes the FLOCW-3 counterweight ideal for use with floats that have longer cables, where it would be time consuming to have to thread said cable through the counterweight.

FLOCW-4

The FLOCW-4 is a heavy-duty, cast-iron counterweight with a WRAS-approved powder coating and a slotted entry for easy cable attachment. The weight’s unique chamfered design means it can be fitted directly over the cable of the float switch – for a larger switching differential, FLOCW-4 is supplied with a rubber collet that grips the float switch cable and expands to hold the counterweight in place, allowing it to be affixed anywhere along the cable.

Float Switch and Counterweight Compatibility

The below table shows the cross compatibility of FLO Series switches and counterweights:

Except for ATEX and potable water applications, each float switch can be used in any medium. FLOCW-4 is the only model suitable for drinking water installation – for ATEX rated accessories, contact a member of the T-T Controls & Automation® team.