Sewer Blockage and Surge Detection wireless transmitters are an award-winning and widely used alternative to using ultra sonics for real-time blockage and surcharge detection in sewers, storm drains, tanks and wet wells.

Using Bulk Dielectric Transducer (BDT) Technology the unit has no moving parts, is easy to install, easy to set up and thanks to its low power consumption has a battery life of 10-years in spite of broadcasting data every 2.5 seconds.

The BDT is ideal for drive-by monitoring or fixed networks where messages can be delivered to existing SCADA, remote data servers or interfaced with BMS/telemetry over distances of many km using our Network Boosters, Gateway Receivers or Cellular Data Concentrators.

Areas the BDT can be used.

  • Detecting Blockages in Sewer Networks
  • Wet Well High Alarms
  • Sewer Surcharge Monitoring
  • Storm Drain Monitoring
  • Industrial & Commercial Sewer Alarms
  • Basement Flooding Alarm

Key Features

bdt wireless level transmitter in drain

  • Set Point from 0.3 m to 4.5 m (10 m optional) depth
  • IP68 100% submersible design 10-year battery life
  • Green HDPE injection moulded transducer housing
  • Real-time 2.5-second read and transmission rate
  • No field programming or software required
  • Installed from the surface to eliminate the need and cost of confined space entry
  • ATEX certified Zone 2
  • Licence Free: EN-300-220 and R&TTE Directive
  • Compatible with RDNET1000TM Boosters and Receivers
  • Supplied with stainless steel mounting bracket
  • Set point simple to set by curling cable
  • Receiver options include: Gateway with relays to telemetry or SCADA, handheld patrol receiver or PC

Download the BDT brochure

Sentinel 4‐Zone Receivers

sewer sentinel receiver


The Sentinel 4 Zone receiver can be supplied to support a wide variety of wireless transducers including BDT Lite blocked sewer alarms, float switch transmitters, lone worker call points, basement flood alarms and site security transmitters.

The receiver is supplied in a smart stainless steel wall box for indoor use and is provided with an internal power supply and bicolour status LEDs for each zone. Simple to install and ready to use the receiver comes complete with internal mutable sounder and dual relay contacts to drive an external sounder, telephone auto dialler or BMS system.

Typically used in Restaurants and Kitchens, retail warehouses, hotels and the leisure industry as well as the railway and airports.

Key Features

  • Stainless steel wall box with custom notation panels in any language
  • Choice of VHF or UHF operation with up to 4‐zones
  • Mains power supply with battery backup option
  • N-type antenna port for local or remote antenna
  • Status LEDs:
  • 4 x bicolour zone LEDs (green = OK, red = alarm)
  • 1 x Fault LED
  • 1 x RX Data LED
  • 1 x Power LEDs
  • CE, EN300‐220 and EN60950 certified

Download the Sentinel Brochure here

RDNET 1000 Gateway Receiver Brochure


Vat GB591551821 Company Number 02906480 – 1994
Dun and Bradstreet, Number (581590544)
NATO Code Number (NCAGE KD520)
EORI Number GB591551821000


Merlin Industrial Products @ 2024 Errors and Omissions Excepted


Call 01752 690622 / 0800 0418 650 (UK)