Automatically Controlled Valves and Accessories

By using this method of classification, automatic control valves can be grouped into three major categories: fluid controlled valves, electrically controlled valves, and fluid-electric-controlled valves. In the latter category a fluid energy generally is used to operate the valve and electric energy is used to control the fluid-energy source. Technical Data used in the field explained in diploma in petroleum technology.

Fhdd-Controlled Valves. The most common types of automatic fluid-controlled valve operators arc diaphragm operators and fluid cylinders. Both of these valve operators can be used on any style of valve body whose inner valve can be positioned by longitudinal displacement of the valve stem. The fluid cylinder operator normally is used with valve-body styles requiring 90” rotation for operation. Diaphragm operators most commonly are applied to valves that have globe, angle, butterfly, and Saunders-type valve bodies. Fluid-cylinder operators are more commonly used with plug valves. Some more details of diploma in petroleum technology are as under.

In oilfield applications, the most common fluid used to actuate both valve operators is natural gas, generally taken directly off a separator or heater-treater on the lease. If natural gas is not available, or if for some reason the available natural gas supply is not suitable, a bottled gas (nitrogen, etc.), compressed air, or hydraulic fluid could be used. Diaphragm operators normally require only 15- to 30-psi fluid pressure to actuate the valve.

Pressures up to 100 psi and over often are desired for the fluid cylinders because, the higher the fluid pressure available to operate the cylinder, the smaller size the cylinder may be, and consequently the lower the cost.

These types of valves generally use the differential pressure principle for control purposes. A reference control pressure is established by spring-loading or prcssureloading the valve operator. The control valve is actuated when the line pressure upstream and/or downstream sensed by the valve operator algebraically exceeds the reference control pressure-i.e., the valve can be actuated by pressures either excessively high or excessively low, or both. This feature makes this type of valve particularly suited for use as safety shut-in valves on wellheads. TSK Training for Skills and Knowledge is the best institute in Rawalpindi Islamabad for Pakistani Students who wants to join diploma in petroleum engineering.