Flue Gas Monitoring

October 8, 2022

Dew Point

October 8, 2022

This article focuses on Environmental & Combustion Controls by Honeywell.

The Environmental & Combustion Controls division includes:

Damper Actuators

Dampers open and close to control the passage of gas (most often air). They are very commonly seen in Air Handlers in central heating systems, burner fire-rate control and wood kilns.

Sometimes they’re used as a safety device to prevent the spread of fire.

The first two examples above are manually operated, but it’s common to operate them electrically by Damper Actuator Motors such as the Modutrol or Direct Coupled Actuators mounted on the shaft of the damper (see picture 3 above)

Homershams supply the actuators to perform this task.

Motorised Actuators & Valves

In the previous section we talked about controlling the flow of air or gas, but these valves control the flow of process water or steam in industrial plants and hydronic water circulating systems. The control is usually determined by an external monitoring system and can be used for diverting the water and/or mixing hot & cold water to achieve a given temperature output.

The Coyote (Ford) has 4-valves per cylinder and can rev higher. The LS (Holden) has push-rods and is limited in maximum RPM and has only 2-valves per cylinder. Yet the push-rod engine remains the choice of many top race engines, included the biggest and baddest, the Top Fuel Drag car.

It's a salient reminder that its much more than just the technology. It's about implimentation and the quality of the driver that makes all the difference.

As mentioned, the valve, or damper is driven by a motor controlling the flow, but the degree of opening and closing is set by Positioning Control.

Positioning control may be

Fixed or On/OFF

As the name suggests, ON/OFF control is simply that. A valve is either 100% open or 100% closed. Sometimes ON/OFF control can overshoot/undershoot, causing poor overall system control.

Floating

Floating control is a variation on the On/Off theme. Floating control requires a fast responding sensor and a slow moving actuator. The slowed response of the actuator ‘smooths out’ the overshoot and undershoot sometime associated with ON/OFF control and can lead to a tighter system control.

Modulating

Modulating controls can open to any degree required by the system e.g. 10% 18% or 75%. Most often the actuator is sent a 4 to 20 mA signal which represents any value between 0 and 100% and can open to that extent.

Gas Detection

Gas detectors sense and alert people to the presence of toxic fumes, explosive gases or diminished (or elevated) oxygen. Gas detectors may be 'person-worn' or installed in-situ with alarms to alert others and log results

Thermostats

Temperature controllers can provide full proportional control of heating and cooling, but sometimes all we need is ON and OFF control and this is the job of the thermostat.

Pressure Control

Pressure switches come in a variety of styles and approvals. DIN, TUV or DVGW approvals are required for some safety applications. Most of these have an adjustable set point to switch contacts, usually to prevent over pressure situations.

Flame Safety/Combustion Control

Burner safety is crucial. Loss of flame, poor burning and other faults can lead to danger and poor burner performance. Burner controls with safety cut-outs and safety interlocks can shut down the system in the event of faults. Additional features such as checking for fresh-air purge before ignition or loss of pilot and other safety features make for a safer system.

Earthquake Switches

Safely shut down processes in the unlikely (!!) event of an earthquake. The switch senses the jolting and/or shock to operate a set of contacts.

When it's time to upgrade - contact Homershams.