STEAM REGULATORS
A globe valve with an electric actuator , such as the Warren Controls ILEA 5800E Series , provides a large turndown ratio and precise modulating control for steam PRV applications .
of reducing steam pressure and flow . The main advantage is that they operate as self-contained devices that do not require electrical power or a pneumatic air supply . The operating principle is relatively straightforward : the valve operates by continuously balancing the downstream pressure ( via a pressuresending pipe ) against a mechanical spring that operates in conjunction with a bellows or diaphragm . The pressure set point is adjusted by tightening or loosening bolts to increase or decrease the spring force . Pilot-operated PRVs have several disadvantages inherent in their design . They provide a limited turndown ratio , typically 10:1 . Therefore , it is quite common that multiple pilot-operated valves are installed in series , often in a 1 / 3 2 / 3 configuration , to produce the net pressure reduction required . These devices are also prone to failure due to clogging by moisture and dirt in the small-diameter pressure sensing pipe and in the valve itself . Steam is used both as the sensing mechanism and as the force for moving the diaphragm . The greatest advantage of pilot-operated valves — operation as a self-contained , isolated device — also serves as an important disadvantage . The ‘ set-it-andforget-it ’ adjustments provide stable downstream pressure , but the pressure cannot be flexibly modulated based on changing load , weather , and other conditions . Pilot-operated valves not only lack the ability to be intelligently controlled , but they are also unable to remotely communicate alerts of problem conditions or data on usage . In fact , a pilot-operated valve provides no visibility of its internal settings and operating condition even when you are standing in front of it .
Electric modulating PRVs
Electric modulating PRVs employ an electric actuator to open and close the valve . Instead of the steam in a pressuresending pipe used by a pilot-operated system , electronic PRVs utilize electrical signals . A controller continuously reads the downstream pressure and temperature from a sensor and uses this information to control the valve ’ s electric actuator . Globe valves with electric actuators provide much more precise control than pilot-operated valves . They have a turndown ratio of 50:1 that supports low loads without the need for 1 / 3 2 / 3 configurations . The systems are more reliable and require less maintenance because the electrical connections eliminate the clogging problems of pilot sensing pipes . Globe valves are also more compact than pilot-operated regulators , making them suitable for confined spaces .
A smarter solution
As a connected system , electric modulating PRVs are fundamentally different from standalone pilot-operated valves . In conjunction with sensors , controllers , and building automation systems ( BAS ), they offer new capabilities of visibility and control . Visibility . The controller has constant visibility of the exact position of the valve . This information is useful in several ways . The pressure reduction station can be monitored remotely , generating alerts of fault conditions . Steam usage data can be captured . The downstream flow rate can be calculated , using the orifice plate method , without installing a flow meter . Control . The PRV can be precisely modulated , and automatically controlled
by logic programmed into the local controller or the building automation system to optimize the system for energy efficiency or performance , and in emergencies , the PRVs can be controlled by personnel accessing the BAS remotely . The ability to remotely monitor and control PRVs is especially useful when pressure-reducing stations are widely distributed at points of use through a large campus or facility and when the steam is used for several different processes .
Bringing steam in line with other systems
As building automation systems become more commonplace , steam pressurereducing stations are sometimes one of the last components to be integrated , long after chillers and boilers have been connected . Electric modulating PRVs have proven to be highly reliable and easy to maintain while providing dramatically improved visibility and control that enables significant energy savings . A college in New England installed a turnkey digital modulating PRV solution engineered by Warren Controls . The facility had a seasonal reduction of steam pressure from 60 PSIG in the fall / winter to 15 PSIG in the spring . A Warren Controls ILEA Globe Valve with Electric Actuator was installed as a PRV after it was determined that a pilot operated pressure reducing valve would suffer poor downstream pressure control and potentially choke steam flow to the heating hot water set when in the late spring / early summer . Also , there was insufficient space for a pilot-operated PRV and insufficient straight run to accommodate a traditional flow meter .
About the author Robert Workosky has served as the Northeast Regional Sales Manager at Warren Controls since 2014 and specializes in control valves and instrumentation , with a particular focus on industry trends and emerging technologies . He is a technical professional with more than 20 years of sales and engineering experience in facilities , HVAC , biotech , food and beverage , and process applications .
36 Valve World March 2024 www . valve-world . net