Have you considered a CDS valve conversion for improving performance and reducing costs on your refrigeration equipment? Over the past ten years, Parker Sporlan has completed tens of thousands of these conversions. Sporlan is well-known for its innovative and economical solution for converting SORIT evaporator pressure regulators on refrigeration equipment into stepper motor-driven CDS valves.
Customer demand for more kits
In response to ever-growing requests from customers for more productivity and cost efficiencies, Sporlan has released its next generation of CDS conversion kits. Nearly all A8 and SPORT pressure regulators can now be converted into Sporlan stepper motor valves using only one of three kits, with a simple retrofit that only takes about 30 minutes.
Sporlan CDS valves are electronically operated step motor evaporator pressure regulating valves. Synchronized signals to the motor provide discrete angular movements of the rotor, which translate into precise linear positioning of the valve piston through a lead screw attached to a series of gears. Valve pistons and ports have an engineered profile, providing high resolution flow performance, and are easily interfaced with microprocessor based controllers. As supermarket refrigeration equipment moves toward greater electronic control, Sporlan’s new conversion kit enables the conversion of a wider range of older mechanical valves to electronic valve control.
A8 and SPORT valves, over time, may fail to operate due to system contamination or develop external leaks at one of the several gaskets. Converting these valves, using electronic CDS conversion kits, is the preferred method when faced with rebuilding a mechanical valve. Conversion also reduces valve complexity and can usually be done in less time than it takes to rebuild the mechanical valve. With the short term advantage of reduced installation labor costs coupled with the longer term benefits associated with upgrading to an electronic modulating valve, it is no surprise that theses CDS conversion kits have become very popular within the supermarket refrigeration industry.
Other advantages include:
Converting to CDS valves saves energy.
- Laboratory testing and field trials indicate a 6-10 percent refrigeration system energy savings is possible after converting EPRs to electric CDS valves. The exact amount of savings is difficult to determine because so many variables are present in a real world supermarket refrigeration system, however, Sporlan has concluded that there is a direct correlation between energy savings and deviation from set-point of a mechanical valve.
Improved control and oil management.
- Mechanical valves require a pressure drop through the valve to function properly and (because they are not always set correctly in the field), refrigerant and/or oil may back up into the condensing unit or evaporator. Because CDS electric valves are easy to set properly, and do not require pressure drop to operate, these back-ups do not occur and the refrigerant and oil is free to return to the compressors.
Conversion allows accurate setting of the valve at any time of year.
- Since a direct correlation exists between the pressure and temperature of a refrigerant due to its thermodynamic properties, outdoor ambient temperatures must be considered when determining set points for mechanical head pressure control valves. It is not uncommon for a supermarket refrigeration system to need adjustments when the ambient temperature changes with the seasons in order to maintain consistent case temperatures. For mechanical valves, this always requires a refrigeration technician to be on site making the required adjustments, however, this is not necessary for electric valves. Since electric valves are electronically controlled, sophisticated algorithms are able to adapt the valve operation to ensure case temperature is maintained throughout all seasonal changes in the ambient conditions.
The temperature and pressure controls allow precise control of air temperature and pressure.
- Through modern manufacturing techniques, today’s electronic sensors have very tight tolerances which ensures incredible accuracy in valve performance. In addition, by using an electric CDS valve in place of a mechanical pressure regulator, the refrigeration system control is able to modulate the valve position based on case temperature rather than refrigerant pressure. This offers a huge advantage to the temperature pull down time when a case comes out of a defrost cycle. Rather than modulating to a specific pressure set-point, which is always attained before the case temperature set-point has been satisfied, the electric CDS valve remains open for case pull-down. The end result is a much quicker pull-down time, and increased product integrity. Controlling off discharge air temperature also allows the case to utilize the available pressure drop to ensure that the case temperature is maintained, even if the case is not running optimally, without experiencing an energy penalty.
Eliminating “blind” components.
- CDS conversion kits are compatible with standard Sporlan Kelvin II Pressure and Temperature Controls and can be integrated into enterprise control systems via MODBUS and BACnet communication protocol. Temperature control is recommended for suction applications to maintain case temperature and pressure control is recommended for high side head pressure control applications. Mechanical valves must be physically set by a technician on site, while electric valves can be set remotely and monitored in real time through the use of an enterprise control system commonly found in today’s refrigeration systems. These advantages are why many supermarkets have converted to electric valves. Complex refrigeration systems can especially benefit from centralized control, saving time and money on service calls and labor costs. For example, commissioning a new supermarket refrigeration system typically takes a 2-3 person team one week to set all the mechanical valves. With electric CDS valves, all the settings can be uploaded to the enterprise control system in a fraction of the time.
No brazing required to complete the conversion.
- Just as the SORIT-to-CDS conversion kit, Sporlan’s next-generation electric CDS conversion kit utilizes the existing valve body installed in the refrigeration system. This means no brazing is required to complete the conversion. Without the need for brazing, extra installation steps such as burn permits and fire spotters, off-hours work, and wet ragging valves to dissipate heat can be eliminated. In addition, if done incorrectly, brazing can damage valves or cables which results in rework and added component costs.
Return on investment
The Sporlan A8, SPORT and A9 CDS conversion kit are a unique aftermarket solution that easily converts existing A8, SPORT, or A9 pressure regulators into modulating, stepper motor driven CDS valves. Valves that qualify for conversion include Refrigerating Specialties mechanical pressure regulators such as the A8A, A81, A82, SPORT and A9 valves. Conversion kits can be driven directly by Sporlan’s Micro Thermo control systems or other common third-party enterprise control systems.
The conversion kit reduces the seal surface area of the installed valve, making it an ideal upgrade opportunity compared to a seal rebuild, or even a full store scheduled retrofit. The conversion provides tight seating for defrost and pump-down applications, requires no pressure drop for operation, and maintains, or slightly increases, the capacity of the valve. In some instances, stability of the system may improve due to the high resolution and accuracy of the step motor actuation incorporated into the electric CDS valve.
Installation typically takes about half an hour. Once the retrofit is complete, the solution pays for itself through improvements in system performance and improved future serviceability and diagnostic capabilities.
Payback is dependent upon the type of application (for example, condenser holdback, EEPR, etc.) and system-specific details, including how well the store is set up or maintained. In general, however, return on investment is typically about two years or less, followed by improved performance, continued energy savings, and reduced maintenance for years to come.
HVACR Tech Tip Article contributed by Jason Forshee, application engineer, Sporlan Division of Parker Hannifin
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