What Materials Can Be Used For Oxygen Service? – if it is a special liquid give specific gravity (at flowing temperate), critical pressure, vapour pressure and viscosity. Through the careful choice of valve type and correct trim design it is possible to minimize the adverse effects of high levels of energy dissipation. Check valves are divided into two types based on check mechanism as:-A. In the presence of most oils and greases oxygen will burn or explode. This occurs with liquids that are viscous, working at low velocities. Some valves have an inherent characteristic that cannot be changed, such as full port ball valves and butterfly valves. Read This, Top 10 commonly asked BPO Interview questions, 5 things you should never talk in any job interview, 2018 Best job interview tips for job seekers, 7 Tips to recruit the right candidates in 2018, 5 Important interview questions techies fumble most. Start. Reduces accounting errors II. What Is The Trim In A Control Valve? Flow rates – Maximum, normal and minimum. The pipeline extension is to be carried out by the customer. In the range from 10 percent to 70 percent of the possible flow rate the pressure variation and the set value (psoll) must not vary more than + 5 percent. Question 19. Are Safety Valves, Regulators And Isolating Valves All Examples Of Control Valves? 60 cm2 c. 62 cm2 d. none of the above View Answer / Hide Answer; Calculate are of a pipe if, flow rate is 20 L/min and flow velocity is 5 cm/s. If pressure ranges are given, the smallest pressure difference is relevant with regards to valve design.. Lessens the risks of intentional irregularities IV. Take the Quiz for competitions and exams. The second is to ensure that the plug and seat are made of a material that can resist the damage (e.g. Control valves are sized according to the application requirements and must satisfy both Cv and velocity criteria. Why Do Different Control Valves Have Different Characteristics? Flashing cannot be eliminated in the valve – if the downstream pressure is less than the vapour pressure then flashing will occur. All Control valves cause pressure drop in the fluid as it passes through the valve. Cavitation is a condition that occurs in liquid flow where the internal pressure of the liquid, at some point falls below the vapour pressure and vapour bubbles form and at some other point downstream rises above the vapour pressure again. What is the function of a butterfly valve? How to define seat leakage class for control valves? Take the quiz, post your results, and challenge your co-workers! Which parameters are important for the selection of the nominal diameter apart from the Kv(s) values)? For other valve types, such as globe, the characteristic can be changed to suit the application. 316) are the best materials for oxygen service in order of preference. The sealing face is part of the valve body and so the separable flanges are only there to hold the body in the line – they are not required to seal. The basic pneumatic valve is a mechanical device consisting of a body and a moving part (poppet or stem), which connects or disconnects passages within the body. Safety valves and isolating valves should not be referred to as control valves without a qualifier such as safety control valve or on/off control valve. 6 things to remember for Eid celebrations, 3 Golden rules to optimize your job search, Online hiring saw 14% rise in November: Report, Hiring Activities Saw Growth in March: Report, Attrition rate dips in corporate India: Survey, 2016 Most Productive year for Staffing: Study, The impact of Demonetization across sectors, Most important skills required to get hired, How startups are innovating with interview formats. The start-up bleeding valves bleed plants with low internal pressure during start-up or filling. Ltd. Wisdomjobs.com is one of the best job search sites in India. Adaptive gain is used for controlling processes. What are avoidable questions in an Interview? 9. Typically in steam conditioning systems some prescriptions in terms of steam velocity are required for a good performance (not lower than..) and therefore the working range of the system may be lower than the “rangeability” of each individual device. Hard face trim (using hard facing materials such as Stellite, or Tungsten Carbide), Increase size of valve, thus reducing the velocity. Will Separable Flanged Valves Seal In A Pipeline? In case of type­1 system steady state acceleration is (a) unity (b) infinity (c) zero (d) 10 Ans: b 74. High recovery valves, such as ball and butterfly, will become choked at lower pressure drops than low recovery valves such as globe which offer a more restricted flow path when fully open. After this point the pressure rises above the vapour pressure again and during this pressure recover stage (recall also the concept of FL) the bubbles collapse, and cavitation takes place. Question 9. In this way ice formation on valve stem is avoided. Valves are defined as devices to control, or regulate the commencement and ——- of air. The pressure drop indicates the active pressure difference between the effective inlet and outlet pressure. Three construction types are distinguished: In many cases the valve is sufficiently dimensioned for a certain application with regards to the Kv(s) value, but it might be too small in respect of nominal diameter and the resulting flow velocities. Question 23. Then we will help you out by providing you with Control Valves Interview Question and Answers on our wisdomjobs site page. The Kv value of the valve should reach this Kvs value. Interview Questions on Control Valves, Control Valves MCQ, Control Valves Objective Questions, Control Valves Multiple Choice Questions. Generally desuperheaters are used in process plants where the steam is used for heating. The trim consists of the parts of the valve that affect the flow through the valve. Thus damages caused by a vacuum will be avoided. Since pressure is a form of Potential Energy, this means that a certain amount of energy is converted from potential energy into some other form. Please see the relevant enquiry sheets for additional information that may assist in the sizing and selection of the control valve required. The vapour pressure of water at ambient temperature of about 25°C is in the order of 4 kPa(a). It occurs when the velocity of the gas or vapour reaches sonic (Mach 1) at the vena contracta. There are then two phases flowing (i.e. Generally the term rangeability is used to describe the capability of a control valve (i.e. It is possible to predict where cavitation will occur by looking at the pressure conditions and the valve recovery factor. Making a great Resume: Get the basics right, Have you ever lie on your resume? Soft Seat Valves are those where either the plug or seat or both are made from some kind of composition material such as Teflon or similar. Back to top. Seat Leakage Classifications There are actually six different seat leakage classifications as defined by IEC 60534-4 std or ANSI/FCI 70.2. During operation they are kept closed by the internal pressure of the vessel. This test comprises of 50 questions on Hydraulics and Pneumatics. Also Read: Control Valves Questions & Answers, Dear sir I want more information for subject thank you sir. Control valves a. In such a case they will act as bleeding valves without venting function. Swing check valve. Difficulty. What Is Incipient Cavitation? Control Systems-Electrical Engineering Interview Questions, Electrical Power System Interview Questions, Industrial Instrumentation Interview Questions, Control Systems-Electrical Engineering Practice Tests, Business administration Interview questions, Cheque Truncation System Interview Questions, Principles Of Service Marketing Management, Business Management For Financial Advisers, Challenge of Resume Preparation for Freshers, Have a Short and Attention Grabbing Resume. Why Is Energy Dissipation An Important Factor In Control Valve Selection? On resetting valves, for example those equipped with a return spring, the —– position is the position assumed by the moving parts of the valve when it … Some plants stipulate that no control valve should be less than two sizes smaller than the line size, other that the valve should not be less than half the line size. Live loading is recommended on applications where a leak along the valve shaft would be likely to cause damage to the shaft and packing. Even the oil deposited on a component by an uncovered hand is sufficient to cause a problem, which is why plastic gloves should be used when building degreased valves. The actuators for many control valves are either spring-to-open or spring-to-close. The outlet pressure indicates the pressure in the system downstream of the valve. The rangeability of the selected valve must exceed the turndown requirements of the application. Seat and retainer ( or disk stack ) overall noise level produced will dissipated. Regulators and Isolating valves all Examples of control valves Objective Questions, control valves interview question and Answers our! Defined as devices to control, or vacuums ) consist of the valve – Turbulent laminar... Specified a passes through the valve body should be less than the two-way isolation, control valves be.! 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