Interview Questions on Control Valves, Control Valves MCQ, Control Valves Objective Questions, Control Valves Multiple Choice Questions, More on Inst Tools. Question 25. Swing check valve. Lift check valve. Control valves are sized according to the application requirements and must satisfy both Cv and velocity criteria. Multiple Choice Quiz: Multiple Choice Quiz This activity contains 15 questions. Valves Objective Questions. ANSWER: c. 2, 3 and 4. Critical temperature is that above which a fluid cannot be liquefied by pressure alone. Noise is created by an object vibrating. To grant this benefit the stem/actuator axis must be in upright position. Specific Gravity Is The Ratio Of The Density Of A Liquid To The Density Of Water – What Is The Specific Gravity Of Gas? The trim consists of the parts of the valve that affect the flow … Question 32. 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. Why is it advisable to extend the pipeline in some cases? In case of toxic or hazardous media the valve must be provided with a closed spring cap (with adjusting screw seal) with leakage line connection. Question 7. On a released valve the forces acting on the cone are compensated on an equally sized release surface owing to the inlet and outlet pressure. The Following Section consists of Multiple Choice Questions on Hydraulics and Fluid Mechanics. Due to the fact that in most applications the pressure drop increases as the flow rate drops, the installed characteristic will normally change from =% towards linear, and from linear towards quick opening. The control valve is most often the final control element of the process industries. The Kv value is a reference value for the flow rate of valves: For engineering a necessary KV value is calculated on basis of the given operating conditions. Temperature – Maximum temperature for design plus temperatures at maximum, normal and minimum flow conditions. If regulating the flow of liquid is highly corrosive then seating material may be of stainles. 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. Control valves a. Next Story. The third is to control where the bubbles collapse and keep this away from vulnerable components (for instance close to internal surface of valve body or pipe). Question 26. The pressure drop indicates the active pressure difference between the effective inlet and outlet pressure. What are avoidable questions in an Interview? Both valves keep the selected set pressure constant. Flashing is a condition that occurs with liquid flow where the pressure falls below the vapour pressure and remains below it. at operating pressure and operating temperature. Bm³ : Volume of the medium (liquid or gas) in the operating mode. increased controlled decreased 3. The less formal control there is in a society, the less there is a need for informal control. 1. Reduced trim is used where it is necessary for the valve to have a Cv capacity smaller than the maximum possible in that size of valve. Attention: Bm³ and Nm³ may often differ from each other owing to the compressibility of the medium. If pressure ranges are given, the smallest pressure difference is relevant with regards to valve design.. 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. The higher the Pressure Drop and the greater the flow rate then more energy will be dissipated. 66.66 cm2 b. However, it is important to recognise that the damage that occurs is dependent on the energy being dissipated and is thus flow dependent.Cavitation sounds like stones passing through the valve. The outlet pressure indicates the pressure in the system downstream of the valve. On a small scale the flow velocity can be reduced to an admissible value thanks to the extended pipeline. Generally the term rangeability is used to describe the capability of a control valve (i.e. 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. There are then two phases flowing (i.e. The term “rangeability” normally refers to a mechanical concept applied to a single throttling device. 1. Choked flow (otherwise known as critical flow) takes place in a valve when an increase in pressure drop across the valve no longer has any effect on the flow rate through the valve. 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. A diffuser is a plate with a large number of small holes in it that is installed in the downstream pipework. These valves have extended bonnets to remove the stuffing box and actuator away from the source of cold and are made of materials such as stainless steel Monel or bronze that do not become too brittle at these temperatures. The working principle of the extended bonnet (named “cold box”) used in cryogenic service (below -100°C) is based on the principle that portion of LNG which evaporates and stagnates in the upper portion of the bonnet has a function of thermal insulation between the process fluid and the gland packing. The continuous bleeding valves are used to evacuate the air accumulating during operation. The internal control system I. (D) … 1 13. Too high flow velocities result in noise, pressure rise and wear and tear. The pressure acting on the control surface closes (pressure reducing valve) or opens (backpressure regulator) the valve against the spring force. Save my name, email, and website in this browser for the next time I comment. Set 1; Set 2; Set 3; Set 4 ) ) ) ) Post navigation. Difference between them, Electrical & Instrumentation QC Interview Questions, for a pressure reducing valve the outlet pressure can be set between 4 and 6 bar, for an overflow valve (back pressure regulator) – the inlet pressure can be set between 4 and 6 bar, for a bleeding and venting valve the valve can be used for this system pressure range, Example 1 : Reduction ratio 20:1 (the regulation data sheet of the valve indicates 20), Example 2 : The nominal value for the outlet pressure 1.2 bar is the highest admissible pv = 20 x 1.2 bar = 24 bar. This means that water will boil at 25°C if the external pressure is reduced to an absolute pressure of 4 kPa. It helps keep the process variable close to the desired point. This test comprises of 50 questions on Hydraulics and Pneumatics. 1, 3 and 4 c. 2, 3 and 4 d. all the above View Answer / Hide Answer. Generally, the globe valves are used as the control valves. Multiple Choice Questions Chapter 1 1. A. pulmonic B. bicuspid ... C. television remote control D. magnet. Question 12. The third is to control the pressure drop and velocities to ensure that the liquid pressure does not fall below the vapour pressure – thus eliminating cavitation altogether. The Mitech control valve actuator has all the parts necessary to reverse the action – this will normally take place in a workshop on site. Fertility is: When people leave an area to go elsewhere that is called: The continent with the lowest population growth rate is: In what stage in the demographic transition theory do death rates fall while birth rates remain high leading to rapid population growth? On-Site assembly a leakage line has to be regulated Positioner controls the relationship between the control unit defective! With choked flow is choked valve must exceed the turndown requirements of Density. Very high turndown applications two types based on check mechanism as: -A the... 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