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.
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.
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 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.
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.