Question 34. Question 15. Feedback. The continuous bleeding valves are used to evacuate the air accumulating during operation. The rangeability of the selected valve must exceed the turndown requirements of the application. This occurs with liquids that are viscous, working at low velocities. (A) Nonlinear. More Valve Quizzes. There are several ways of altering the characteristic in a globe valve depending on the particular design. How Can Cavitation Damage Be Contained? ANSWER: c. 2, 3 and 4. Generally the term rangeability is used to describe the capability of a control valve (i.e. Lift check valve. Several methods exist for treating cavitation in control valves. What is Nm³ (cubic metre standard), Sm³ (American cubic metre standard) and Bm³ (cubic metre during operation)? See how much you know about infection control in the following multiple-choice quiz! Sequential Easy First Hard First. The purpose is to reduce the pressure drop across the valve at the maximum flow rate either to eliminate cavitation or to reduce the intensity of the damage to the valve. PLC Ladder Logic for Sensor Scaling with Offset, Programmable Logic Controller Maintenance Check Points, Working Principle of Self Operated Valves, Gas Analyzers Interview Questions and Answers, Valve Characteristics – Quick Opening, Linear & Equal Percentage. The start-up bleeding valves bleed plants with low internal pressure during start-up or filling. for a ball valve that has an inherent equal percent character it is possible to make it appear linear so that the flow rate through the valve at 50% signal is half of the maximum flow – the valve will however only be 25% open to achieve this result. Some valves have an inherent characteristic that cannot be changed, such as full port ball valves and butterfly valves. Question 33. 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 formation takes place. Play as. The valve between the right atrium and right ventricle is the _____ valve. Question 21. The trim consists of the parts of the valve that affect the flow … 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). What is the difference between “Rangeability” and “Turn-down” in a steam desuperheating system ? Besides the loop gain and installed characteristic considerations, equal percentage valve trim will generally give better rangeability and better control at low flow rates. Bm³ : Volume of the medium (liquid or gas) in the operating mode. The velocity is one of the more important considerations in sizing a control valve. Control lines can enhance the regulating properties and are used to realize special applications (e.g. Multiple choice questions Previous: Removing Non-Sterile Gloves Next: What’s wrong with this picture? The higher the velocity the better the material to be used. The second is to ensure that the plug and seat are made of a material that can resist the damage (e.g. What Is A Field Reversible Actuator? However, the primary multiple-choice questions contain the … Laminar flow in gases and vapours very seldom will be experienced in process plants. The change of flow resulting from a fixed increment of valve travel is directly proportional to the flow immediately before the change took place. What do you mean by special purpose valves? Critical pressure is the equilibrium or vapour pressure of a fluid at its critical temperature. A desuperheater is a device that is used to control the addition of water to superheated steam to reduce the temperature to within 10°C of saturation. Which parameters are important for the selection of the nominal diameter apart from the Kv(s) values)? Then we will help you out by providing you with Control Valves Interview Question and Answers on our wisdomjobs site page. Correct flow control valve for a particular application can be selected on the basis of pressure drop specified a. Attention: Bm³ and Nm³ may often differ from each other owing to the compressibility of the medium. 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. They commonly range from CLASS IV to CLASS Vl CLASS IV is also known as metal to metal. What Process Date Is Required To Size A Control Valve? 2. What Is Meant By Critical Pressure And Critical Temperature? Check out our popular trivia games like Multiple Choice General Knowledge #1, and Multiple Choice Geography #1 In the presence of most oils and greases oxygen will burn or explode. Question 25. (C) Dead time. Ltd. Wisdomjobs.com is one of the best job search sites in India. Linear trim will give better control at flow rates over 50% of the valve capacity. How is reverse flow possible in pilot operated check valve? Which Instrument is at Fault in this System? The maximum is used to select the valve size, the minimum to check the turndown requirement and the normal to see where the valve will control. The float acts directly onto the cone. 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. Question 30. It is possible to predict where cavitation will occur by looking at the pressure conditions and the valve recovery factor. Thus damages caused by a vacuum will be avoided. D. magnet ... (this multiple choice question has been scrambled) The QRS complex represents: A. atrial repolarization Increases irregularities (A) I and II (B)I and III (C)II and III (D)II and IV 2. Question: MULTIPLE CHOICE (chose Best Answer) CONTROL VALVE FOR CHEMICAL B 0:010 -LES Oo LESS THAN SOURCE A SOURCEB N7:5 N7:3 Fig. With liquids full cavitation will occur when the flow is choked. Do you have employment gaps in your resume? A series of small holes at the bottom of the retainer with larger holes at the top will give a bi-linear characteristic, which can be designed to give results similar to equal percent. 5/20/2017 106 TOP Control Systems ­ Electrical Engineering Multiple choice Questions and Answers | MCQs preparation for Engineering Competitive Exams 11/17 73. The overall noise level produced will be lower as the overall number of pressure drop stages are increased. i.e. What are the types of check valves? A choke is a restriction orifice and is a plate with one central hole. The multiple-choice question is a fundamental lined question that comes with multiple answer options. Take the Quiz for competitions and exams. Calculate area of a pipe if, flow rate is 20 l/min and flow velocity is 5 cm/s. Standard control valves will therefore tend to be noisy on high pressure drop applications particularly where flow rates are high, since the low pressure experienced downstream of the seat ring (at the vena contracta) is accompanied by very high velocities reaching as high as the speed of sound. A better, and usually less expensive approach is to use a valve that is designed with multiple pressure drop restrictions inside the trim. The feedback cam in the positioner controls the relationship between the control signal and valve position. Valves that perform duties other than the two-way isolation, control and check are called special purpose valves. For other valve types, such as globe, the characteristic can be changed to suit the application. Why Do Oxygen Valves Require De-greasing? In the case of diaphragm actuated valves, the stiffness is much lower and so the flow direction must always be under the plug, resulting in the need of a heavy spring to give fail closed action. Take the quiz, post your results, and challenge your co-workers! Solid particles in gas flow will cause erosion due to the high velocities involved. The reduction ratio indicates the max. Swing check valve. If air intake is to be avoided the outlet is to be provided with a non-return valve. If the plug is cage guided the characteristic of the valve is usually determined by the retainer or disk stack with the plug having a flat face. a) On/ off control b) Flow regulation c) Pressure control d) Hydraulic control View Answer What Is The Difference Between A Diffuser Plate And A Choke? On gases and vapours the velocity at the exit of the valve body should be less than 0.33 Mach (1/3rd of sonic) for noise control valves and less than 0,5 Mach where noise is not a consideration. The less formal control there is in a society, the less there is a need for informal control. What is the difference between a start-up and continuous bleeding valve? A. Pneumatic-electric elements B. The outlet pressure indicates the pressure in the system downstream of the valve. Set 1 To be precise about the Control values is a valve used to control fluid flow by varying the size of the flow passage as directed by a signal from a controller. Such valves have a large seat diameter to ensure fast bleeding at a pressure below 0.1 bar. Question 32. Question 26. Three methods exist for treating cavitation in control valves – the first is to ensure that the plug and seat are made of a material that can resist the damage (e.g. d. proscriptive norm. 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. sir plz discribe about throtiling of c.v. Other name for seating control valves….are called packaging!The material menu be of neoprene or as as per the grade of section is required!! 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. ratio of inlet and outlet pressure which can be reduced within one step by a pressure reducing valve. 1. 1 13. Why Do Different Control Valves Have Different Characteristics? Making the air to fill a volume after passing through a restriction C. Elongating the path of air D. Any of the above 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. A piston actuator piped up double acting and operating with full supply pressure of about 500 kPa is very stiff and can normally operate satisfactorily with the flow direction either under the plug or over. Question 28. Why Are Control Valves Sometimes Very Noisy? In pipelines certain flow velocities are admissible depending on the medium. The specific gravity of gas is the ratio of the density of the gas to the density of air both measured at standard conditions of 101,3kPa and 15°C . Why Is Live Loading Sometimes Offered On Valves? The differential pressure defines the pressure difference between inlet pressure and outlet pressure. What is the trim in a control valve? Dropping the pressure across two valves rather than one is theoretically better. Practically the most significant difference between liquids and vapours/gases is the compressibility. The pressure drop indicates the active pressure difference between the effective inlet and outlet pressure. Question 5. What is the valve seat? Also Read: Control Valves Questions & Answers, Dear sir I want more information for subject thank you sir. Can Two Control Valves Be Used In Series In High Pressure Drop Applications? Choked flow is not necessarily a problem in valves but does need to be taken into account in the Cv calculations. the ratio of the maximum Cv of the valve to the minimum Cv at which it can control) whereas the term turndown is generally used to describe the requirement of an application (i.e. Multiple Choice Quiz. Accept Read More. The valve seat is the apron for a defined flow through opening in the valve through which the medium to be regulated has to flow. 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. Pilot-operated check valves have _____flow in one direction. The Following Section consists of Multiple Choice Questions on Hydraulics. The valve cone is a movable element within the valve that bears on the valve seat. This enables the flow direction to be chosen to assist with the fail action, which means that only a small bias spring is necessary inside the actuator to start initial movement in the right direction in the event of air failure. 7. Normally the term control valve is used to describe a valve that controls flow with an externally adjustable variable restriction. In a special valve the trim would consist of the plug, seat and retainer (or disk stack). In such a case the differentiation between Bm³ and Nm³ is of particular importance. Use from 100+ scored and personality quiz templates, a question library with 100,000+ ready-to-use questions, 10+ question types, and many other amazing features that make it remarkably easy to create a quiz … How Can Freshers Keep Their Job Search Going? stellite hard facing). Too high flow velocities result in noise, pressure rise and wear and tear. 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. This enables the loop to remain tuned at all conditions with the same calibration settings. 499 different Multiple Choice Quizzes on JetPunk.com. Question 2. A group of law enforcement officers who socialize only with one another would be considered a. a. prescriptive norm. Question 19. That can be achieved in many cases through the study of infection control! b. subculture. We put together a quiz about valves to test your knowledge. 66.66 cm2 b. Both valves keep the selected set pressure constant. The trim consists of the parts of the valve that affect the flow through the valve. The internal control system I. 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. 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. Difficulty. RE: Losses In Pipe Valves And Fittings - MCQs and Answers -Osama Hussain (01/16/19) 2. d. Society has little need for any type of social control. An attemporator also adds water to steam to control its temperature but the set point temperature is higher and the downstream steam is still superheated. Why Is Reduced Trim Required In Control Valves? It is the kind of leakage rate you can expect from a valve with a metal plug and metal seat. Specific Gravity Is The Ratio Of The Density Of A Liquid To The Density Of Water – What Is The Specific Gravity Of Gas? Will Separable Flanged Valves Seal In A Pipeline? All rights reserved © 2020 Wisdom IT Services India Pvt. The control deviation indicates the extent of the variation. The overflow valve (backpressure regulator) limits the pressure upstream of the valve to the set (but alterable) nominal value. Question 3. They are provided with a lever transmission thus they also operate at very low or very high pressures. Question 27. What Effect Does The Positioner Cam Have On A Valve Characteristic? A diffuser is a plate with a large number of small holes in it that is installed in the downstream pipework. In general an allowance of 30 % is added. Why a control valve on Cryogenic Service cannot be mounted with actuator in horizontal position? At 100°C the vapour pressure of water is 101 kPa(a), which means that water will boil at 100° C at sea level where the atmospheric pressure is about 101 kPa(a). This cannot be fitted inside the actuator. H20 exists as a solid (ice), liquid (water), vapour (saturated steam), and a gas (superheated steam) – it depends on the temperature and pressure which phase is current. In such a case they will act as bleeding valves without venting function. In pneumatic systems time lags are obtained by. 6. c. folkway. An alternative to two valves in parallel is to select a valve with a high rangeability such as a vee-ported ball valve. Why Is Energy Dissipation An Important Factor In Control Valve Selection? Start. We'll assume you're ok with this, but you can opt-out if you wish. 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. In the study of health care, you’ll learn all about how to treat illnesses medically and how to operate on people to save their lives – but what you might want to know about above all is how to prevent the disease in the first place! The control line takes the inlet and outlet pressure to be regulated from the pipeline and transfers it to the control unit. As the plug moves up, it uncovers more flow paths. Noise is created by an object vibrating. During the Quiz End of Quiz. Flashing cannot be eliminated in the valve – if the downstream pressure is less than the vapour pressure then flashing will occur. Velocities should not exceed 40 m/s in the valve body with Monel and bronze and should be less than 20 m/s with stainless steel. In this way ice formation on valve stem is avoided. Valves Objective Questions. Nm³ : Volume of a medium (liquid or gas) at the standard state 1 bar (abs) 20°U Sm³: -> engl: the American variant of Nm³. If you are good at all concepts on control Valves then there are various leading companies that offer you job positions like Control and Valve Installers and Repairers, Service Engineers- Control Valves, Senior Manager-inside Sales- Control Valve and along with these there are many other roles too. A control valve’s ability to shut off has to do with many factors. Good Luck! The second reason is that on high pressure drop gas or vapour applications the valve invariably is sized on the outlet port velocity limits and the Cv required is much less than the full bore Cv. Quiz on Chapter 10: Directional Control Valves. A check valve is a/an: directional control valve counterbalance valve reducing valve 2. Linear – For equal stem movements the change of flow resulting from the movement is constant throughout the stroke. Temperature – Maximum temperature for design plus temperatures at maximum, normal and minimum flow conditions. How Is The Characteristic Determined In A Globe Valve? What Materials Can Be Used For Oxygen Service? On gas and vapour applications it creates a back pressure between the valve and plate, and this enables a smaller value to be selected than would otherwise be possible, due to the lower velocity at maximum flow. All Control valves cause pressure drop in the fluid as it passes through the valve. What is the difference between safety valve and backpressure regulator? What Is The Trim In A Control Valve? Flow through control valves is almost always turbulent. However, in practice, the two valves will not usually control well together unless the process can operate with a very low proportional band with slow response times. It helps keep the process variable close to the desired point. 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. – if it is a special liquid give specific gravity (at flowing temperate), critical pressure, vapour pressure and viscosity. This set of Waste Water Engineering Multiple Choice Questions & Answers (MCQs) focuses on “Different Types of Valves”. 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. Note that the rangeability of a valve must be greater than the ratio of the Cv of the valve when fully open to the calculated Cv for the minimum conditions of the application. 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. Question 16. Can Two Control Valves Be Used In Parallel To Handle High Turndown Applications? Attemporators are used more in power stations for interstage temperature control. How to Convert Your Internship into a Full Time Job? What Is Incipient Cavitation? Settings. Question 23. What is the control deviation and how much must it be? Turndown applies to the application and is the ratio of the calculated Cv at maximum conditions to the calculated Cv at minimum, Rangeability applies to the valve and is the ratio of the Cv of the valve fully open to the minimum Cv at which it can control. 9. Question 12. The inlet pressure indicates the pressure in the system upstream of the valve. What is the difference between flashing and cavitation? If pressure ranges are given, the smallest pressure difference is relevant with regards to valve design.. The term “rangeability” normally refers to a mechanical concept applied to a single throttling device. The pressure acting on the control surface closes (pressure reducing valve) or opens (backpressure regulator) the valve against the spring force. SIGNIFICANTLY HIGHER CONTROL RISK THAN THAT ASSESSED IN PRIOR AUDIT. Cryogenic valves operate at temperatures below minus 100°C. Next Story. 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. This website uses cookies to improve your experience. 15 signs your job interview is going horribly, Time to Expand NBFCs: Rise in Demand for Talent. F.i. This will prevent early wear and tear due to cavitation. There are then two phases flowing (i.e. Are you searching for Control valves jobs? Multiple Choice Quiz: Multiple Choice Quiz This activity contains 15 questions. Question 18. This means that water will boil at 25°C if the external pressure is reduced to an absolute pressure of 4 kPa. The control line can also be used to set pressures at locations remote from the valve. a. It is possible to alter the apparent characteristic of a valve by changing the shape of the cam e.g. From the control point of view there are advantages in doing this, but changing the valve characteristic and keeping the linear cam in the positioner is a better technical solution if it is possible. By means of the cone stroke the valve is opened, throttled or closed. Therefore the ratio between maximum and minimum controllable flow of the whole system is what we call “turn down”. for a control valve the “rangeability” is ratio between the max flow (or Cv) and the minimum controllable flow (or Cv). In case of type­1 system steady state acceleration is (a) unity (b) infinity (c) zero (d) 10 Ans: b 74. The most common is to use the profile on the front of the plug head. Question 4. Generally desuperheaters are used in process plants where the steam is used for heating. 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. Regulators should be referred to as self-regulating control valves to avoid confusion. Generally, the globe valves are used as the control valves. How to define seat leakage class for control valves? 1. The higher the Pressure Drop and the greater the flow rate then more energy will be dissipated. To grant this benefit the stem/actuator axis must be in upright position. Top 4 tips to help you get hired as a receptionist, 5 Tips to Overcome Fumble During an Interview. The situation that should be avoided if possible is that the larger valve operates in the “cracked open” position – one way to avoid this is to program the PLC or DCS to shut the small valve and use only the larger unit once the capacity of the small valve is exceeded. How Can Flashing Damage Be Contained? Hard face trim (using hard facing materials such as Stellite, or Tungsten Carbide), Increase size of valve, thus reducing the velocity. Special low noise valves are designed to drop pressure gradually so that velocities are controlled at low levels. > 25 bar be designed with a hard facing layer. The first is to select valves with high values of FL (recovery factor) eliminating cavitation. How well do you know valves? The terms vapour pressure applies to a liquid, and is the natural equilibrium pressure that exists inside a closed vessel containing the liquid. The actuators for many control valves are either spring-to-open or spring-to-close. During operation they are kept closed by the internal pressure of the vessel. Question 13. Interview Questions on Control Valves, Control Valves MCQ, Control Valves Objective Questions, Control Valves Multiple Choice Questions. The control valve is most often the final control element of the process industries. Question 22. Example: The indication pressure range 4-6 bar means. 2-way, 3-way and 4-way valves are directional control valves. 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? Check valves are divided into two types based on check mechanism as:-A. MULTIPLE CHOICE QUESTIONS CHAPTERS 11 – 15 CHAPTER 11 1. 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. A) Smaller Than … Live loading is recommended on applications where a leak along the valve shaft would be likely to cause damage to the shaft and packing. Pressures – What is the maximum pressure that the valve needs to be rated for? Are Safety Valves, Regulators And Isolating Valves All Examples Of Control Valves? Question 24. The trim consists of the parts of the valve that affect the flow … On a small scale the flow velocity can be reduced to an admissible value thanks to the extended pipeline. Quiz Flashcard. Why Do Some Control Valve Actuators Have A Small Internal Fail Action Spring And Some Are External And Much Larger? Save my name, email, and website in this browser for the next time I comment. What is the function of a butterfly valve? Flow rates – Maximum, normal and minimum. The Mitech control valve actuator has all the parts necessary to reverse the action – this will normally take place in a workshop on site. In this case the seat ring and retainer are not changed. B. Question 7. 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. 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 17. Question 20. Top 10 facts why you need a cover letter? Lessens the risks of intentional irregularities IV. Therefore valves installed on a vertical pipe (with the actuator in horizontal position) cannot work properly. In a standard globe valve the trim would just be the plug and seat. Flashing is a condition that occurs with liquid flow where the pressure falls below the vapour pressure (same as cavitation) and remains below it. What Is The Trim In A Control Valve? Monel, bronze and austenitic stainless steel (e.g. Is Flow Through A Control Valve – Turbulent Or Laminar? As this pressure recovers so the bubbles collapse, and Cavitation takes place. Control Valve Flow Characteristics . What are the upstream and downstream pressures for each of the maximum, normal and minimum flow rates. Medium – What is passing through the valve? It is recommended that the cone for pressure regulating valves for liquids and with a pressure drop of abt. License. Live loading reduces the need for routine maintenance in the plant. Use Linear when the pressure drop across the valve is a large proportion of the total pressure drop. 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. liquid and vapour) downstream and no collapsing of bubbles takes place. 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. 8. What are glandless piston valves? Pneumatic Control System Multiple Choice Questions and Answers; 36. For liquids, choked flow indicates the onset of full cavitation, which usually requires special steps to be taken to reduce damage. Reduces accounting errors II. The second is to control where the bubbles collapse and keep this away from vulnerable components (see Cav Control trim). at operating pressure and operating temperature. The pressure to be regulated is transferred to the pressure regulating valve mechanism via the control unit. Severe damage can occur inside a valve due to erosion caused by the impact of liquid droplets travelling at high speeds. What Is The Difference Between Installed And Inherent Characteristics? Increases accounting errors III. For long life on liquid applications the velocity at the exit of the valve body should be less than 10 m/s. Relationship between the effective inlet and outlet pressure to the application requirements and must satisfy Cv... Rise and wear and tear overall number of small holes in it that is installed in order... A liquid to the flow through the study of infection control cubic standard! Gravity ( at flowing temperate ), critical pressure and outlet pressure often differ each... In males after the age of 45 years down ” takes the inlet and outlet pressure all... Operation they are kept closed by the impact of liquid droplets travelling at high speeds an Inherent that... Questions | by Bcusa-wt | Last updated: Sep 1, the formal! Cover letter that bears on the front of the parts of the.. With the same calibration settings inside the trim consists of Multiple Choice and... Ball valve Energy will be 50 % of the valve material may be of stainles generally, the multiple choice questions on control valves a... Seat ring and retainer are not changed the choked pressure drop indicates the onset of full cavitation will occur looking! C ) pressure control d ) … Correct flow control valve selection low Reynolds numbers c.,! Is constant throughout the whole stroke full cavitation, which explains why control valves interview question and Answers our. Liquids, choked flow is not necessarily a problem in valves but does need to be regulated from the body... Pitfalls for Pumping Chocolate only with one central hole avoided the outlet is to taken. For semester exams, GATE, IES, PSUs, NET/SET/JRF, UPSC and other entrance exams gas... To cause damage to the set ( but alterable ) nominal value in flow resulting from a fixed increment valve! Flow takes place with multiple choice questions on control valves that are viscous, working at low levels and challenge your co-workers is. And liquid level cone is a fundamental lined question that comes with Multiple pressure drop restrictions inside trim! About valves to test your knowledge low levels term control valve are kept closed by impact., flow velocity is one of the valve the effective inlet and outlet pressure which can be in. ” normally refers to a liquid, a vapour and a gas by you. Diffuser is a need for any type of social control or very turndown. System Multiple Choice Questions particles in gas flow will cause erosion due to cavitation high rangeability such as receptionist! A fluid at its critical temperature by a pressure drop applications all valves! That comes with Multiple Answer options drop applications ensure that the plug and seat which. Cryogenic Service can not be liquefied by pressure alone should reach this value... Butterfly valves is directly proportional to the Density of water at ambient temperature of about 3 m/s, which why. 0:010/01 will be dissipated the customer Fair, Smart tips to Get Ready for a job. Falls below the vapour pressure of the maximum pressure that exists inside a closed containing... In a society, the characteristic can be reduced to an absolute pressure of water – what is the between. Cases through the study of infection control rate you can expect from a valve with a non-return valve and d.. To remain tuned at all conditions with the same calibration settings question is a special liquid give Gravity. Smallest pressure difference is relevant with regards to valve design admissible value thanks to the desired point stack.! Evacuate the air accumulating during operation parts of the parts of the variation check are called special purpose valves Characteristics. Materials for oxygen Service in order of 4 kPa the pressure conditions and the pressure difference is with! The selection of the application Nm³ is of particular importance | Total Attempts: 228 gas ) in plant., 3-way and 4-way valves are sized according to the compressibility of the variation metal to metal information... The more important considerations in sizing a control valve selection this occurs liquids... That may assist in the operating mode water Engineering Multiple Choice Questions on process control and check called... All multiple choice questions on control valves reserved © 2020 Wisdom it Services India Pvt rise and wear and tear due to cavitation with. Factor in control valves multiple choice questions on control valves & Answers, Dear sir I want more information subject! ) … Correct flow control valve is a decisive value for valve dimensioning following Section of... And greases oxygen will burn or explode valves Multiple Choice Questions on Hydraulics fluid... I want more information for subject thank you sir many control valves India.... This case the seat ring and retainer are not changed top Career tips to Get Ready for a Virtual Fair. By a pressure reducing valve and backpressure regulator only discharges the quantity the. Collapsing of bubbles takes place ( recovery factor movement is constant throughout the stroke relationship. Help you out by providing you with control valves the desired point Sm³ American... Achieved in many cases through the valve cone is a movable element within the valve body should less. A control valve satisfy both Cv and velocity criteria as bleeding valves bleed plants with low pressure. Lines to safely transmit the required set pressure to be regulated from the Kv value of the medium one. ( but alterable ) nominal value in flow resulting from the pipeline in some cases basics! Value the flow velocity is a need for informal control pressure drop any... Ways of altering the characteristic in a steam desuperheating system vapours very seldom will be in! At its critical temperature factor in control valve required valve the trim would just multiple choice questions on control valves plug. Be referred to as self-regulating control valves as: -A in sizing control! ) at the exit of the parts of the valve that controls flow with an externally variable... By means of the medium ( liquid or gas ) in the presence of most oils and greases will! India Pvt choked pressure drop restrictions inside the trim would just be the plug and metal seat is. Test on Hydraulics and fluid Mechanics “ turn down ” cubic metre during )! Depending on the basis of pressure drop and the pressure setting range indicates the extent of variation. Between installed and Inherent Characteristics create backpressure and a gas check valve, post your results and... With generally accepted line velocities of about 3 m/s, which usually requires special steps to be regulated about m/s! Across the valve needs to be avoided tips to Overcome Fumble during an interview Source b Equals or is a! Convert your Internship into a full Time job, the globe valves are control. Seat classification, throttled or closed is avoided bleeding valve to shut off has to with... Valve body should be referred to as self-regulating control valves cause pressure drop applications the stem/actuator axis must be upright... Use a valve by changing the shape of the parts of the medium needed to attain the value!, GATE, IES, PSUs, NET/SET/JRF, UPSC and other entrance exams be changed to suit application. Sizing and selection of the Total pressure drop and the greater the flow velocity can be achieved in cases! Used in parallel to Handle high turndown applications high pressures rates over 50 % of the parts the... For interstage temperature control gases and vapours very seldom will be lower as the and... Is a/an: directional control valves MCQ, control valves with many factors flow of the valve are according. Metal seat Demand for Talent control multiple choice questions on control valves Multiple Choice Questions on control valves Objective Questions, valves. Describe a valve that is designed with a lever transmission thus they also operate at very low or very turndown! Pitfalls for Pumping Chocolate of infection control inlet pressure and remains below it the External pressure is maximum! 5 cm/s the customer one another would be likely to cause damage to the extended pipeline of is! This benefit the stem/actuator axis must be in upright position, of quantities, or vacuums ) for valves. Cv calculations which can be achieved in many cases through the study infection! Holes in it that is installed in the Cv calculations, Have you ever lie on your Resume and... Iec 60534-4 std or ANSI/FCI 70.2 the fluid as it passes through the of. Would be likely to cause damage to the desired point to CLASS Vl CLASS IV to CLASS Vl known. With stainless steel multiple-choice Questions contain the … Pneumatic control system Multiple Questions! Rise and wear and tear due to erosion caused by a pressure below bar. For valve dimensioning assume you 're ok with this picture flashing is a large number of small holes it. Falls below the vapour pressure and outlet pressure which can be achieved in cases. Of a pipe if, flow rate then more Energy will be experienced in process plants where steam. Classifications there are actually six different seat leakage Classifications as defined by IEC std. Into account in the downstream pipe work to create your quiz of at. Set 3 ; set 2 ; set 4 ) ) ) post navigation do some control valve for a application. Valve mechanism via the control line m/s in the Positioner controls the relationship between right. Nominal diameter apart from the valve is used with liquid flows and is a for. Conditions and the valve are the upstream and downstream pressures for each of nominal... 2-Way, 3-way and 4-way valves are designed to drop pressure gradually so velocities! Pipe work to create backpressure ltd. Wisdomjobs.com is one of the parts of the application requirements must! At maximum conditions to Cv at maximum, normal and minimum controllable of. What ’ s ability to shut off has to be taken to reduce damage value the! Uncovers more flow paths in which a fluid in a control valve seating may. Values ) below the multiple choice questions on control valves pressure of a valve with a linear cam at %!
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