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Feature the other hand , it also allows full-flow pressure into the HVAC unit . Together , they help improve the efficiency of your HVAC system significantly .
Automated Control Solutions
Automated Control Solutions
Danfoss ABQM DN250 at a local data centre .
The most common control valves in an HVAC system are the following :
• Butterfly valves , ball valves and plug valves assist in controlling the ventilation and heating of an air conditioner . Others are diaphragm valves , gate valves and knife gate valves .
• Triple-duty valves for cooling and heating hydronics , are a part of many HVAC systems . They simultaneously act as balancing valves , check valves and shut-off valves . There are also automatic flow , limiting valves that control the speed pumping system to regulate water flow in an HVAC unit .
• Some contain pressure reducing valves that control the water pressure in this loop , and / or circuit setter valves that maintain a specific amount of water flow through the piping loop in an HVAC .
Control valves are critical for HVAC systems . They play an essential role in ensuring that they operate efficiently and last for an extended period .
HVAC systems contain varying fluids which depend on the pressure range operated by actuators . Control valves assist in controlling the forces regulating the pressure range in HVAC systems . They prevent the actuators from letting the pressure reach its maximum level – once pressure starts touching the upper limit , the valves divert excess oil to bring the pressure down . In addition to this , valves also help release cracking pressure in HVAC fluids .
The control valve plays a crucial role when it comes to pressure overriding in an HVAC unit . On the one hand , it regulates cracking pressure that allows HVAC fluids to pass quickly . But on
The New Danfoss ABQM4 FCU Valve .
SAFETY RELIEF VALVE REPLACEMENT , MAINTENANCE AND INSTALLATION Safety relief valves are relatively maintenance-free devices , though periodic visual inspection should be made to verify the condition of the valves . While performing this inspection , some of the conditions to watch for are :
Signs of corrosion that could make a valve malfunction
• Broken or missing seal wires
• Valve leakage
• Missing nameplate
• ‘ Stacked ’ relief valves
A major question concerning relief valves is , when and how often should the system relief valves be changed ? They should be changed out after discharge to ensure safeguarding a system with a properly set relief valve . Most systems are subject to accumulations of piping debris such as metal shavings and solder impurities , as the system is fitted for installation .
These impurities are generally blown into the relief valve seats at the time the valve is discharged . The impinged debris then inhibits the relief valve from reseating at its original set pressure . Valves are then found to relieve at considerably lower pressure settings than the stamped valve setting , due to the force of the reclosing action .
The International Institute of Ammonia Refrigeration ( IIAR ), in its Bulletin 109 , IIAR Minimum Safety Criteria for a Safe Ammonia Refrigeration System , recommends that the relief valve be replaced or inspected , cleaned and tested every five years .
ANSI STD K61.1-1989 , Safety Requirements for the Storage and Handling of Anhydrous Ammonia , is very specific in its requirements . Paragraph 6.8.15 states :
“ No container pressure relief devices shall be used after the replacement date as specified by the manufacturer of the device . If no date is specified , a pressure relief valve shall be replaced no later than five years following the date of its manufacture .” RACA
REFERENCES 1 . IIAR 2 . https :// www . achrnews . com / articles / 94640-safety-reliefvalve-replacement-maintenance-and-installation
3 . https :// www . scienceworldreport . com / articles / 61696 / 20200730 / what-is-the-function-of-controlvalves-in-an-hvac-system . htm
4 . https :// www . valin . com / resources / articles / best-practicespipe-and-valve-selection-for-cooling-system
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RACA Journal I January 2024 www . refrigerationandaircon . co . za