Float Switches – Part 2 of a series on Lift Station Components.
In this Series: Exploring the ins and outs of liftstation components and discussing how all the parts or pieces of a pump station come together to move America’s wastewater. We will look at the common problems of old stations and help you understand the pieces and locate the parts to keep the caca flowing. Check out the first installment of this series of Lift Station Components when we looked at Float Switch Brackets. Buy Float Switch Brackets
Quick Pitch: Lift Station Floats and Pump Station Floats: Up / Down, Normally Open / Normally Closed / SPDT (Single Pole Double Throw) – What does it all mean and what should I use?
Float switches are the simple signalling devices that tell the pumps in lift stations to come on and off. Float switches can also signal low levels in basins and pits and signal sewage backup and liftstation high level alarms and low level alarms. Float switches are a critical component and not all are created equal. Today we will look at float switches from from Conery Mfg. Conery Manufacturing was founded in 1979 and produces high quality equipment and components for the water and wastewater industry. They make the legendary Conery 2900 Series Float Switches for liftstations, pump stations, sump pumps and pump pits.
Float switches come in three different flavors
- Normally Open Float Switches
- Normally Closed Float Switches
- Single Pole Double Throw Float Switches
This is the most common float switch used in lift stations and sump pumps for pump down applications. Normally Open simply means the contacts of the switch are open when the float is in the hanging down position (or vertical). In pumping applications this normally means the pump is off when the float is hanging down. Normally open float switches are available in Narrow Angle Float Switches or Wide Angle Float Switches.
Normally Open Wide Angle Float Switch contacts are closed (Or pump turns on) when the float rises 45 degrees above horizontal. These float switches are the most commonly used floats and are recommended for sump pumps, lift station pumps, and general pumping applications.
The normally open wide angle float switches that are pump duty rated can also be provided with a piggy back plug that allows you to directly control the pump or sump pump through the float. They are normally available in P1 (120V) and P2 (220V).
Normally Open Narrow Angle Float Switch contacts are closed when the float rises to 5 degrees above horizontal or approximately 1 inch above horizontal. These are typically used for alarms or when there is a narrow band of liquid that needs to be measured. Narrow Angle float switches are not normally recommended for direct connection to pumps as they can cause pump “chatter” due to the narrow angle of switch actuation.
Normally Open Float Switches are also used to signal high water levels in sump pumps, pump stations and liftstations.
Buy Normally Open Float Switches
Normally Closed Float Switch contacts are closed (Or switch on) when are typically used for pump up applications or as a high float to cut off pumps.
Normally Closed Narrow Angle Switch contacts become open and turn off the switch when the float rises 1 inch or 5 degrees above horizontal. These are typically used when you need to measure a narrow band of water or wastewater but are not recommended for direct pump applications due to the “pump chatter” caused by the narrow band.
Normally Closed Wide Angle Switch contacts become open and turn off the switch when the float bulb rises 45 degrees above horizontal. These are the normal float used in conjunction with pump applications as the wide angle keeps the pumps from coming off and on too quickly.
Normally Open / Normally Closed or SPDT Float switches are a variation of the N/O and N/C float switch. This float switch can be wired to operate based upon the wiring setup you need . It can be either a normally open or a normally closed switch but not both at the same time. These switches are slightly more costly but can really save you time and money if you don’t know what type of switch you need or you can’t decide which switch you should stock as a spare.