June 15, 2021 

This notice serves as formal communication of Critical Environment Technologies (CET)’s decision to discontinue the QCC Quad Channel Controller. CET will maintain replacement units and parts until the End of Service timeline is reached for customers with a valid warranty. 


TABLE 1: End of Service Timeline 



End of Sale Notification Date

June 15, 2021

Last Time to Buy

August 15, 2021

Last Ship Date

September 15, 2021

Warranty Period*

2 years from date of purchase

End of Service and RMA Support

July 15, 2023

Last Day Replacement Parts are Available

July 15, 2026**

 *Please refer to our Terms and Conditions of Sale for more information.

**Or sooner based on material availability.


Reason for Termination: 

CET is committed to providing class leading products to our customers by engineering better gas detection solutions. With the introduction of our new 4 channel Flexible Control System (FCS) we have determined that there is no need to continue with the QCC given the better performance of the FCS over the QCC. 


Replacement Product and Backwards Compatibility: 

We are pleased to introduce a 4-channel model of our high performing FCS Flexible Control System that replaces the QCC. 

Introduced in 2017, the FCS is a proven system controller that offers a more robust user experience with a large, full color LCD resistive touch screen, data logging and an additional relay and horn/strobe connection. The FCS also utilizes a real time clock and offers data logging, enhanced logic control, zoning and extra priority structure capabilities. 

The FCS-4 comes standard with 4 Modbus® RTU RS-485 connections for 4 digital transmitters. If analog transmitters are required it can be ordered with 4 analog inputs (option -AI). With the AI option, the FCS-4 can accommodate digital and/or analog transmitters up to a maximum of 4 gas channels. 

The FCS-4 offers Modbus® RTU RS-485 (model: FCS-4-M) or BACnet® MS/TP RS-485 (model: FCS-4-B) output for communicating with a BAS or DCC. 

Other familiar features like the size of the enclosure, audible alarm, ability to connect to the same peripheral devices and option to add a top mounted strobe, manual shutoff switch and internal heater remain the same.


TABLE 2: QCC to FCS-4 Equivalency Table 




FCS-4-M (add Option -AI for 4 analog inputs)


FCS-4-B (add Option -AI for 4 analog inputs)


Should a QCC system in the field need replacing, the FCS-4 can make all the same connections as the QCC, plus it offers more features. If the QCC system has analog transmitters, the FCS-4 will need to be ordered with the -AI option.


TABLE 3: Comparison of Features between the new FCS-4 and the old QCC





Large, full color LCD resistive touch screen LEDs

LCD display with push buttons



4 SPDT dry contact, rated 5A @240VAC

3 SPDT dry contact, rated 5A @240VAC

4 Inputs

Modbus® and/or 4 – 20 mA analog

Modbus® and/or 4 – 20 mA analog


Modbus® or BACnet®

Four 4 - 20 mA (Option -AO)

2 horn/strobe terminals

Modbus® or BACnet®

Two 4 - 20 mA (Option -AO)

1 horn/strobe terminal

Data Logging


came with Option -AO

Door Lock & Keys

Ability to lock the enclosure to prevent unauthorized access (Option -DL)


Top Mounted Strobe

Option -L

Option -L

Manual Shutoff Switch

Option -SW

Option -SW

Watertight Buzzer

Option -WA

Option -WA

Internal Heater

Option -IH

Option -IH


60 priorities for channels, relays, strobes and horns and internal buzzer with logic controls:

·         Gas Concentration

·         Calibration Expired

·         Time of Day Control

·         Title-24 Occupied

Analog output tracks single channel, peak or average of channels, step and/or VFD with optional time delays in step mode

8 priorities for channels, relays, strobes and horns and internal buzzer with logic controls:

·         Gas Concentration




Analog output tracks single channel, peak or average of channels 

Firmware Updates

USB port

USB port

pdf version