Water & Waste Water 

Control Systems

P.O. Box 318, Towanda, IL 61776 | 815-515-9599

STELTEC's HL Series controllers use Oxidation Reduction Potential (ORP) and/or pH to provide precise control of water chemistry.  However, the system is robust enough to handle unexpected variations in your plant's flow.  Recirculating and once-through systems are both offered.


This series of control systems feature STELTEC's proprietary NTL control logic.  NTL has been designed to handle even difficult-to-control once-through applications where PID controllers are not suitable.


There are two HL models, based on the number of channels required.  All HL systems feature:


  • Color Touch Screen: Easy to see, intuitive to operate
  • Mini Web Server (Ethernet): Any web browser on the network can monitor the controller
  • Live Trending:  See what's happening in real-time
  • Data Logging: Store up to 4 years of data readings

NTL: Newton's Third Law


For every action, there is an equal and opposite reaction.


NTL is designed to make control changes only after the passing of a calculated lag time, thereby preventing overshooting and undershooting. 


Designed for: 

  • Long lag times (greater than 1 minute)
  • Variable lag time
  • Variable flow rates
  • A variable measured parameter

the NTL control logic will ensure that a steady setpoint is maintained.

HL Series ORP/pH Controllers