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Need help with your application? Contact us for expert advice on Nestec flow switches and indicators.

ABLE are the exclusive manufacturer and support provider for the Nestec flow product range and can assist you and your customers in the following areas:

  • Application expertise across the full Nestec flow switch product range
  • Our factory trained engineers offer after-sales support
  • Nestec product training, either in person or via video call

Further to the above, ABLE can offer customised solutions based on your individual requirements. Email us now at info@247able.com

Nestec 21000 Series Flow Switch

High‑Flow Piston Flow Switch with 2″ Connections and Custom Thresholds

ABLE Instruments are the UK manufacturer of Nestec flow switches and indicators, including the 21000 Series; high-capacity mechanical flow switches designed to handle elevated flow rates in industrial and process environments. The Nestec 21000 Series is engineered for large bore pipework and applications where significant flow volume must be monitored reliably. With its 2″ BSP process connection, this model is ideal for pump monitoring, cooling systems, industrial water loops, and plant-wide process control circuits.

Inside the switch body, a spring-loaded piston moves in response to fluid flow, triggering a magnetically isolated reed switch. The flow threshold can be adjusted at the time of order to suit your application. As with other Nestec switches, the electrical contact is completely separated from the process media, ensuring long-term reliability even in systems with pulsating flow or particulates.

Key Features:

  • High-flow capacity: Designed for 2″ pipelines and elevated flow rates
  • Mechanical piston detection: Spring-loaded piston with no electrical parts in contact with media
  • Adjustable switch thresholds: Flow setpoints customisable at time of order
  • SPST or SPDT contacts: Magnetically actuated reed switch for clean and safe switching
  • Built for process reliability: Withstands pulsating flow and minor particulates
  • Durable construction: Stainless steel or brass versions available

Have a particular project in mind? We’d welcome a call on +44 (0) 1189 169 420

Constructed from stainless steel or brass with rugged internals, the 21000 Series is made for demanding operating conditions. It is typically used in HVAC systems, pump skids, manufacturing lines, or filtration processes where both high flow and robust signal integrity are needed.

This model is available with either SPST or SPDT switch types, and optional customisation on thread type and switch setting can be discussed with ABLE’s engineering team.

21000 Series Specifications:

Technology
Mechanical piston with magnetically actuated reed switch
Switch Type
SPST or SPDT dry contact
Connection Size
2″ BSP (other threads available on request)
Wetted Materials
Brass or stainless steel
Flow Range
Up to 100 L/min (media and configuration dependent)
Ingress Protection
IP65
Ambient Temp Range
−20 °C to +80 °C
Summary
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