A valve handwheel is a common type of valve actuator. This means it is used to regulate the opening and closing of a valve manually. There are different types of valve handwheels, and you should understand how they work before you decide to buy one. In this article, we will go into details of different types of valve handwheels, including their designs and specifications, so you'll know what to look out for during your purchase.
Valve handwheels fixed to stems provide a mechanical advantage. However, in high temperatures, these types of handwheels fixed are susceptible to thermal binding. When you shut off a valve while it is hot and allow it to cool, it can get stuck, making it impossible for you to reopen the valve. This is an apt description of thermal binding.
A hammer handwheel comprises a primary wheel, lug, and secondary wheel attached to a threaded stem. This attachment allows you to shut the valve tightly for closure. Based on the design, the primary wheel moves through a portion of its turn freely and then hits against the lug on its secondary wheel.
Most knife gate valves have handwheels through 24 inches (DN 600). You'll need a low torque bearing handwheel assembly for heavy-duty equipment, consisting of a heavy-duty Fabri-Valve yoke assembly fitted with a roller bearing stem nut.
Another thing to note here is rim-pull which is the amount of force you need to exert on the handwheel to open or close the valve. Typically, rim-pull remains within reasonable limits, but this is not always the case. It may exceed these limits depending on a combination of factors like the valve's service conditions and packing drag. Another common cause of this is when the pressure drops across the valve.
If the rim-pull exceeds reasonable limits, you can use bevel gear operators to regulate the force. Here's a simple chart to help you choose a handwheel for your valve.
Valve handwheels are designed for installation on the yoke of globe valves. As you operate the handwheel, take extra care not to add friction to the actuator. Also, use link mechanisms for handwheels on rotary valves so that control of the valve position is not lost when the handwheel is engaged. Handwheels with gears are connected to pinion shafts to allow one person to operate them.
Valve position indicators (VPIs) use mechanical counters to convert the valve's open and closed positions to electronic signals. With this, you are sure to send out accurate valve signals to your control room and avoid any form of injuries plus damage.
You can install VPIs on new and existing valves, even when they are under pressure. These indicators are handy in explosion-proof areas, and the best part about them is, you don't have to bother about regular maintenance. VPIs provide second safety by detecting valve position independent of the actuator.
A VPI consists of a range of sensors and switches fixed into a protective housing of stainless steel. The body of the VPI and other coupling materials are made from stainless steel 316. It also has a custom-made coupling attached to the valve.
At Reid Supply, we provide high-quality valve handwheels in different designs. Beyond valve handwheels and other handwheels, we also stock various machine handles such as crank handles, revolving handles, iron handwheels, and plastic handwheels. Along with positioning indicators and other industrial hardware.
Visit our website today to browse through our catalog and find the right fit for your machinery.
If you have any questions just call us at 1(800) 253-0421 or send an email to firstname.lastname@example.org.