Machine Room Control

Process Monitoring and Control

You want your operation, whether it is food manufacturing, freezing, cold storage, packaging, or other automated process, to be accurately monitored and controlled. Empire Control Systems incorporate state-of-the-art technology to provide the precision you need, and the ability to see exactly how your process is doing at a glance.

Temperature, pressure, level, flow, speed, oxygen or carbon dioxide gas concentration, ammonia detection, energy consumption, production totalization, or whatever your process requires - our PC based system can do it efficiently, accurately, and reliably. Our system will give you confidence that your product is the highest quality possible.

Manage your process using highly accurate sensors and intelligent PID logic to precisely control fans, valves, motors, actuators, and other devices. Incorporate variable speed technology for fine control, energy efficiency, a quieter and more comfortable environment, and other benefits.

Enjoy the ability to really “see” what is happening in your facility. The accuracy and quantity of the sensors installed in strategic locations throughout the plant provide an understanding of your process never before possible. Greater efficiency, increased production, reduced product loss, and reduced maintenance is often realized with a Empire Controls monitoring and control system.

If you've got a process, we've got a system to accurately monitor and control it!

Condenser Monitoring and Control

Auto Discharge Pressure Setpoint

Ambient temperature and relative humidity readings are used to calculate the wet bulb temperature, the ideal limit for evaporative cooling, which is then used to determine the discharge pressure setpoint. This setpoint is constantly recalculated to utilize all the available condensing capacity under the current ambient conditions. The minimum discharge pressure setpoint is user adjustable. Condenser Fan Sequencing

Condenser fans sequence on when the discharge pressure is above setpoint for a time delay period, and sequence off when the pressure falls below setpoint. Condenser fans will typically be set up so the fans will come on in order of the smallest to largest. Under heavier load conditions this order can be reversed, allowing the larger fans to come on first. When two fans are of similar size, either one can be selected as the lead fan.

Variable Speed Control

Condenser fans can be operated over a range of 0 - 100% of full speed. This takes advantage of the cubic fan law, which is that the power required to drive the fan varies as the cube of the speed. In other words, the energy consumption of the fan motor drops off dramatically as the speed is reduced. Refer to the graph at the right for a better understanding of this fan power curve.

Variable speed technology is very well suited for condenser fans because all available fans can run together at the same speed, thus utilizing the entire surface area of the coils while dramatically reducing the power consumption. The system uses intelligent control algorithms to operate the fans at the speed required to match the refrigeration load, eliminating the need to continually start/stop the motors to control capacity.

Condenser Pumps

The user enters the start/stop pressures of each pump. Generally the pumps run all the time, but in cold weather the pumps will sequence off when the discharge pressure falls below the stop setpoints. When the pressure rises again, the pumps will sequence back on according to their start setpoints.


Non-condensables are detected in the system by comparing the discharge pressure with the pressure corresponding to the measured liquid condensate temperature. A gauge on the condenser control screen displays the non-condensable pressure to enable the user to know when purging is required.

Compressor Monitoring and Control

Auto Suction Pressure Control

Every refrigeration system has specific requirements for suction pressure. However, these requirements may change significantly depending on the season, product, ambient temperature, etc. If the suction pressure is too high, the zone temperatures will not be maintained at the desired setpoints. If the suction pressure is lower than necessary, energy efficiency and compressor capacity are unnecessarily degraded. Auto suction pressure control optimizes the compressor operation by automatically determining the best suction pressure for existing conditions.

Capacity Control

Whatever the suction pressure setpoint, operating compressors will efficiently load or unload in a coordinated pattern as the pressure varies. Generally, the largest compressor loads first, followed by the next largest compressor, etc. Unloading follows the reverse order.

Screw compressors load or unload as determined by a Proportional, Integral, Derivative (PID) algorithm that considers a number of factors to calculate the rate that the capacity is changed. In order to minimize slide valve position “hunting”, the control system suspends capacity control adjustments when the pressure is within the user determined deadband setpoints.

Variable speed technology is very well suited for capacity control as well. The system uses intelligent control algorithms to operate the compressor at the speed required to match the refrigeration load, eliminating the need to continually adjust the slide valve. The slide valve can remain 100% loaded while the motor speed varies for maximum efficiency.

Flexible Compressor Sequencing

An important function of intelligent compressor control is to determine which compressors will be operated for a given refrigeration load. We provide the user with an easily configured matrix that allows complete flexibility in selecting the compressors that will operate at each sequence step. If a compressor is out of service or the facility load pattern changes, the sequence steps can be re-defined with a few clicks of the mouse.

The sequencer steps up when the suction pressure is above setpoint, and steps down when the system detects that the load on the operating compressors is small enough to be handled by the next lower sequence step. All sequencer parameters such as pressure deviation, tonnage differential, and time delays are user adjustable to enable customized tuning of the system.

Alarm Conditions

The system continuously monitors the compressors for a fail to start condition, or a slide valve fail to load condition. If either of these alarms occur, the operator is immediately notified in order to prevent out-of-spec conditions in the facility.

System Wide Approach

Look at the “big picture” and control your compressors as part of the overall system, not as individual pieces of equipment. Keep the heart of your system operating at maximum efficiency and reliability. You won't believe how simple it is to select capacity control and compressor sequence parameters to fit your plants changing control needs. Make sure that you have the capacity you need, when you need it, without wasting energy and without accumulating unnecessary run hours on compressors.