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Types of Check Valves

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CHECK VALVE (NON RETURN VALVE-NRV)

Check valve is used to stop back flow in a piping system. This is also called Non return Valve (NRV)

Check valves are available in the following designs:

  1. Swing Check Valves
  2. Tilting Disk Check Valves
  3. Wafer Check Valves
  4. Disk Check Valves
  5. Piston Check Valves
  6. Ball Check Valves
  7. Duo-Check Valves
  8. Non-Slam Check Valves

SWING CHECK VALVE :

swing check valve Theory

Swing Check Valves are available in straight body design and y-pattern design. The disk is suspended from the body by means of a hinge pin and seals against the seat which is integral with the body. These valves are typically used in sizes 2 inches and over. Swing check valves can be installed in both horizontal and vertical position. They are not suitable for pulsating flow.

Closure response of swing check valve is slower compared to lift check valve due to longer disc travel and inertia of disk.

Industry Codes and Standards

  • Valve Design :     BS 1868 / API 6D
  • Pressure Testing : BS 6755-I
  • Face To Face : ANSI B 16.10
  • Flange Drilling : ANSI B 16.5 / BS 10 Table / DIN / IS / JIS Std.
  • Butt Weld End : ANSI B 16.25
  • Face to Face : ANSI B 16.10
  • Socket Weld End : ANSI B 16.11
  • Screwed End : ANSI B 1.20.1(BSP/NPT)

TILTING DISK CHECK VALVE

TILTING DISK CHECK VALVE Operation

Tilting Disk Check Valves fit between two flanges and provide a compact installation for large diameter applications.

These valves can be installed in horizontal and vertical lines.

They provide a quick closing response and are particularly suited for pulsating flows with compressible fluids.

WAFER TYPE CHECK VALVE

WAFER TYPE CHECK VALVE THEORY

Wafer Type Check Valve has short face-to-face dimensions and low weight allows a simple space saving installation between the companion flanges. The valves are suitable to mounting between weld neck or slip on type companion flanges of different standards.

They are specially developed for applications where a low-pressure loss is essential. Opening and closing of the valve will take place at an extremely low-pressure difference over the valve disc. The eccentric disc shaft combination with the disc seat guarantees a positive shut off returning media. Wafer check valves are becoming the preferred type of check valve for most applications, due to their compact design and relatively low cost.

DISC CHECK VALVE

DISC CHECK VALVE THEORY

The Single Disc Check Valve (Wafer Type Disc Check Valve) consists of four main components: the body, a disc, a star guide and a spring. The Disc check valves are opened by the pressure of fluid and closed through compression spring as soon as flow stops thus preventing reverse flow.

The design of Wafer Design, Sandwich Type Single Disc Spring Loaded Check Valves allows them to be installed between any flanges of different standard and in any position; including vertical pipelines where the fluid flows downwards.

DISC CHECK VALVE THEORY OPERATION

PISTON CHECK VALVE

PISTON CHECK VALVE THEORY

Piston Check valves are generally used to protect pumps or similar equipment, allowing the flow only in one direction and preventing flow reversal due to back pressure. The piston check valves are designed with globe valve bodies, producing an increased drop pressure in the pipeline. This design provides a tight seal as well as a fast reaction to the closure impulse. Metal seated check valves may not provide drop tight sealing when used in gas system or fluid system with low back flow pressure or fluids containing particles.

BALL CHECK VALVE

BALL CHECK VALVE THEORY

The ball check valve is one of the few check valves that works well in both water and wastewater applications. Ball check valves are simple in operation and commonly used on small pumps and in low head systems. Consider adding an optional roll-bar to the piping system for safety; ball check valves have the highest tendency to slam due to the ball’s high inertia long stroke. When ball check valves encounter high pressures and dynamics, severe slamming may result.

DUAL PLATE WAFER CHECK VALVE

DUAL PLATE WAFER CHECK VALVE THEORY

The Dual Plate, Wafer Check Valve employs two-spring-loaded plates hinged on a central hinge pin. When the flow decreases, the plates close by the action of torsion spring before flow reversal takes place. All features put together make the Dual Plate Check Valve as the most efficient & versatile design. It is also referred to as SILENT CHECK VALVE. It is much easier to install between standard gaskets and line flanges, and therefore is more cost effective to install and to maintain. Its design complies with API 594 and API 6D, testing with API 598. It is also called as Butterfly Check Valve.

NON-SLAM CHECK VALVE

NON-SLAM CHECK VALVE THEORY

The swing check valve closes abruptly because of gravity, and causes pressure surge resulting in shock waves. These high pressure waves causes sever stress on the piping system. This problem can be minimized by installing a Non-Slam type check valve. Non-Slam check valve do not rely on gravity. As the upstream velocity of the fluid slows the spring assist on the valve start to close the disc. By the time the upstream velocity comes to 0, the disc is completely closed. With the reverse flow eliminated, the force necessary to produce water hammer on either side of the valve are substantially reduced.

Maintenance – Preventive, Predictive, Proactive, Corrective

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Whether you own a car,house ,building  or professionally involved in operation and maintenance of  machines, you need to know  some basics about maintenance.

Some form of maintenance you are practicing already but you always need to re-look at maintenance program so that you keep your asset(s) in correct form with minimal cost.

Maintenance is not only “the restoration of any asset to function after it has failed “instead spectrum of maintenance is broadened now.

This post covers the basic maintenance types with special focus on following topics related to maintenance Programs.

  • Maintenance definition
  • Objectives of maintenance
  • Nature of maintenance
  • Types of maintenance programs
  • Comparison of maintenance programs

Maintenance definition

British Standard Glossary of terms (3811:1993) defined maintenance as:

“The combination of all technical and administrative actions, including supervision actions, intended to retain an item in, or restore it to, a state in which it can perform a required function”

Maintenance is a set of organized activities that are carried out in order to keep an item in its best operational condition with minimum cost acquired.”

In general, Maintenance means to hold, keep, sustain or preserve the building ,machine or structure to an acceptable standard.

Objectives of Maintenance Program

  • Maximising production or increasing facilities availability at the lowest cost and at the highest quality and safety standards.
  • Reducing breakdowns and emergency shutdowns.
  • Optimizing resources utilization.
  • Reducing downtime.
  • Improving spares stock control.
  • Improving equipment efficiency and reducing scrap rate.
  • Minimizing energy usage.
  • Optimizing the useful life of equipment.
  • Providing reliable cost and budgetary control.
  • Identifying and implementing cost reductions.

Types of Maintenance Programs

Different types of maintenance are being practiced in various parts of world.Adoption of particular Maintenance type greatly depends upon the resources of organization or company.One maintenance approach may cost less than other so each professional has to see the resources and then decide for “which maintenance type is best for his plant”.

types of maintenance programs

 

Reactive or Corrective Maintenance

Reactive maintenance is basically the “run it till it breaks” maintenance mode. No actions or efforts are taken to maintain the equipment as the designer originally intended to ensure design life is reached.

Reactive or Corrective Maintenance

Advantages to reactive maintenance can be viewed as a double-edged sword. If we are dealing with new equipment,we can expect minimal incidents of failure. If our maintenance program is purely reactive, we will not expend manpower dollars or incur capitol cost until something breaks.

Advantages of reactive maintenance

Disadvantages of reactive maintenance

  • Increased cost due to unplanned downtime of equipment.
  • Increased labor cost, especially if overtime is needed.
  • Cost involved with repair or replacement of equipment.
  • Possible secondary equipment or process damage from equipment failure.
  • Inefficient use of staff resources

Preventive Maintenance

Preventive maintenance can be defined as follows:

“Actions performed on a time- or machine-run-based schedule that detect, preclude, or mitigate degradation of a component or system with the aim of sustaining or extending its useful life through controlling degradation to an acceptable level.”

Preventive maintenance frequency may be machine operating hours based or after fixed time interval as decided by maintenance engineer or recommended by vendor of machine.

Advantages of Preventive maintenance

  • Cost effective in many capital intensive processes.
  • Flexibility allows for the adjustment of maintenance periodicity.
  • Increased component life cycle.
  • Energy savings.
  • Reduced equipment or process failure.
  • Estimated 12% to 18% cost savings over reactive maintenance program.

Disadvantages of Preventive maintenance

  • Catastrophic failures still likely to occur.
  •  Labor intensive.
  • Includes performance of unneeded maintenance.
  • Potential for incidental damage to components in conducting unneeded maintenance. 

Predictive Maintenance

Predictive maintenance can be defined as follows: Measurements that detect the onset of a degradation mechanism, thereby allowing causal stressors to be eliminated or controlled prior to any significant deterioration in the component physical state. Results indicate current and future functional capability. Basically, predictive maintenance differs from preventive maintenance by basing maintenance need on the actual condition of the machine rather than on some preset schedule. You will recall that preventive maintenance is time-based. Activities such as changing lubricant are based on time, like calendar time or equipment run time.

For example, most people change the oil in their vehicles every 3,000 to 5,000 miles traveled. This is effectively basing the oil change needs on equipment run time. No concern is given to the actual condition and performance capability of the oil. It is changed because it is time.

This methodology would be analogous to a preventive maintenance task. If, on the other hand, the operator of the car discounted the vehicle run time and had the oil analyzed at some periodicity to determine its actual condition and lubrication properties, he/she may be able to extend the oil change until the vehicle had traveled 10,000 miles. This is the fundamental difference between predictive maintenance and preventive maintenance, whereby predictive maintenance is used to define needed maintenance task based on quantified material/equipment condition.The advantages of predictive maintenance are many.

A well-orchestrated predictive maintenance program will all but eliminate catastrophic equipment failures. We will be able to schedule maintenance activities to minimize or delete overtime cost. We will be able to minimize inventory and order parts, as required, well ahead of time to support the downstream maintenance needs. We can optimize the operation of the equipment, saving energy cost and increasing plant reliability.

Advantages of predictive maintenance

  • Increased component operational life/availability.
  • Allows for preemptive corrective actions.
  • Decrease in equipment or process downtime.
  • Decrease in costs for parts and labor.
  • Better product quality.
  • Improved worker and environmental safety.
  • Improved worker moral.
  • Energy savings.
  • Estimated 8% to 12% cost savings over preventive maintenance program.

Disadvantages of predictive maintenance

  • Increased investment in diagnostic equipment.
  • Increased investment in staff training.
  • Savings potential not readily seen by management.

Proactive Maintenance

The latest innovation in the field of predictive maintenance is so-called pro-active maintenance, which uses a variety of technologies to extend the operating lives of machines and to virtually eliminate reactive maintenance.

The major part of a pro-active program is root cause failure analysis, which is the determination of the mechanisms and causes of machine faults. The fundamental causes of machine failures can thus be corrected, and the failure mechanisms can be gradually engineered out of each machinery installation. It includes routine preventive and predictive maintenance activities and work tasks identified from them.

typical maintenance practices

It has been known for a long time that imbalance and misalignment are the root causes of the majority of machine faults. Both of these conditions place undue forces on bearings, shortening their service life.Rather than continually replacing worn bearings in an offending machine, a far better policy is to perform precision balance and alignment on the machine, and then to verify the results by careful vibration signature analysis.

Among above maintenance types, Proactive maintenance programs has privilege of having advantages which are sum of advantages of each of reactive maintenance ,preventive maintenance & predictive maintenance program.While it shares its disadvantages mostly with predictive maintenance program.

Predictive maintenance vs Proactive maintenance

  • Predictive maintenance is the technique to determine the condition of machine by sensing, measuring tools etc.
  • Example- Suppose one fan having abnormal vibration that find out by sensing tools (vibrometer etc. ) and we attend the job and rectified the current problem in fan. but in proactive maintenance , we search-out the main cause of the problem, which may, design problem, weather problem, operation problem etc, that to solve the actual problem.

Heat Transfer Loops in HVAC System

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Several heat transfer loops work in an HVAC system. In these heat transfer loops heat energy is exchanged to achieve the ultimate purpose of heating and cooling of air inHVAC system.

These heat transfer loops are basic organs of any HVAC system. Problem in any of these loops affects the HVAC system .In these heat transfer loops thermal or heat energy moves from left to right as it is extracted from the space and rejected into surroundings or air through five loops of heat transfer.

Heat transfer loops in HVAC system

Figure – Heat transfer loops in HVAC system

  1. Indoor air loop in HVAC system

In the left loop, indoor air is driven by the supply air fan through a cooling coil, where it transfers its heat to chilled water. The cool air then cools the building space or different HVAC zones.

  1. Chilled water loop in HVAC system

Driven by the chilled water pump, water returns from the cooling coil to the chiller’s evaporator to be re-cooled.

  1. Refrigerant loop in HVAC system

Using a phase-change refrigerant, the chiller’s compressor pumps heat from the chilled water to the condenser water.

  1. Condenser water loop in HVAC system

Cooling water absorbs heat from the chiller’s condenser, and the condenser water pump sends it to the cooling tower.

  1. Cooling tower loop in HVAC system

The cooling tower’s fan drives air across an open flow of the hot condenser water, transferring the heat to the air.Thus cooling tower rejects heat to atmosphere in this way.

Capacity Control of Absorption Chillers

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Capacity of absorption chillers needs to be adjusted with respect to load on HVAC water chillers. Capacity control of HVAC chillers is very logical and required to save the input energy at low or part-load on chillers.

Chillers providing absorption cooling use different types of input energy. Absorption chillers are generally controlled from input energy being provided to  generator(single effect absorption chillers) or high pressure generator (double effect absorption chillers). 

Absorption chiller
How capacity of absorption Chillers is controlled ?

Capacity of absorption chillers is controlled by varying the input thermal energy to generator.While input thermal energy to absorption chillers is regulated with reference to load on chillers .Suppose load on absorption chillers changes then the outlet temperature of chilled water will also be changed little and this is generally sensed by chiller instrumentation. Chiller controller now regulates the valve of thermal energy with respect to the change in thermal load.

Capacity Modulation of Absorption Chiller as load decreases

As load decreases  chilled water temperature decreases .When chilled water temperature decreases below predetermined set point,gas valve (in case of direct fired chillers) will start closing accordingly . As burner fire rate or steam flow rate is modulated chilled water temperature will be changed accordingly.This decrease in load would cause closing of steam inlet valve in case of steam operated absorption chiller (indirect fired chillers).

This closing of valve will reduce the heat input to generator of absorption chillers and temperature in generator will be reduced. By this technique of capacity modulation, heat input to chiller is lowered  in generator so accordingly less vapors of refrigerant (water in lithium bromide chillers) will be produced .These vapor get condensed in condenser of chiller and finally reach the evaporator of chiller at lower pressure.Now because less vapors reach evaporator so less heat will be extracted from chilled water and refrigeration effect will be reduced and chilled water temperature will increase accordingly.

Mass flow rate of refrigerant is directly proportional to load and refrigeration effect.

Generally between 30 and 100 percent of the hvac system design refrigeration load, the burner fired rate is modulated. Below 30 percent of design hvac load, the burner is cycled on and off, and all refrigerant and solution pumps remain.

On the other hand ,concentration of solution reaching the absorber from generator will drop accordingly.In other words as less thermal energy is supplied to generator of chillers, solution reaching the absorber will be less strong as it would still contain some  refrigerant. This little less strong solution will have less capacity to absorb refrigerant vapors as compared to strong solution.So accordingly more vapors will remain in evaporator and would increase the evaporating temperature and pressure in evaporator of absorption chiller. Finally a new balance will be established between gas inlet valve and load to achieve the preset temperature at outlet of evaporator.

Capacity Modulation of Absorption Chiller as load Increases

Similarly if load on HVAC absorption chiller increases then chilled water temperature will also be increased accordingly.Chiller need to be adjusted in accordance with this new load value.Gas valve or steam inlet valve will be opened more to adjust the refrigeration effect and load on chiller.Rest of effect will be inverse of load decrease.

HVAC Double Effect Absorption Chiller

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Double effect absorption chiller is an improvement in single effect lithium bromide chiller. Double effect water chillers have more coefficient of performance and enhanced utilization of input energy.Basic working principle of these dual effect absorption chillers remains same as single effect but with addition of some components to vapor absorption cycle.
Absorption cooling is enhanced using the system energy which would have been otherwise wasted as in case of single effect industrial chiller.In order to produce chilled water in these double effect chillers, water remains as a refrigerant and lithium bromide as absorbent in these HVAC water chillers. As compared to single effect  absorption chillers,double effect vapor absorption chiller has an additional heat exchanger and generator/concentrator.

Basics of Double effect Absorption Chiller Operation

HP Generator Process in Double effect Absorption Chiller Operation

In double effect absorption chiller,both in direct and indirect fired chiller operation, weak solution from the absorber is pumped into the HP generator through LT, condensate and HT heat exchangers. It is heated by operating steam and concentrated to the intermediate solution, and high temperature refrigerant vapor is produced.Instead of steam ,hot exhaust gases or waste heat may also be used as in case of direct fired absorption chillers.

LP Generator  and HT exchanger Process in Double effect Absorption Chiller Operation

In next step of chiller operation,Intermediate solution enters LP generator through HT heat exchanger in exchanging heat with weak solution which is passed through the tubes. Intermediate solution in LP generator is heated by the refrigerant vapor from HP generator, concentrated to the strong solution, releasing refrigerant vapor at the same time.

LT Heat exchanger Process in Double effect Absorption Chiller Operation

The strong solution passes through the outside tube space of LT heat exchanger, enters absorber, transmitting heat to the weak solution from absorber. In absorber the strong solution absorbs refrigerant vapor again.

Condenser Process in Double effect Absorption Chiller Operation

Refrigerant vapor from HP generator is condensed in LP generator to form condensate, which enters condenser through throttle. Refrigerant vapor formed in the LP generator flows to the condenser to form condensate also.

Evaporator ,Refrigerant Pump and Absorber Process in Double effect Absorption Chiller Operation

At normal temperature and pressure water boils at 212oF but as pressure is lowered sufficiently below atmospheric pressure then boiling temperature is also decreased .Same thing is used in evaporator of absorption chillers (single and double effect ).

These two parts of refrigerant condensate flows into the flash chamber through U pipe. A part of refrigerant water is flashed to form vapor, which flows into the re-absorption chamber at the bottom of absorber, while another part of refrigerant water is cooled, and enters evaporator refrigerant pan. Refrigerant from evaporator refrigerant pan is pumped over the evaporator tubes for the refrigeration effect, and evaporates to form vapor by absorbing heat of chilled water flowing through tubes.

Produced refrigerant vapor enters absorber, and absorbed by strong solution in the absorber. Chilled water is cooled and return to the HVAC system of customer. Strong solution is diluted by absorbing refrigerant vapor in absorber and absorbing flashed refrigerant vapor in the re-absorption chamber.

Solution Pump in Double effect Absorption Chiller Operation

Weak solution  is then transferred by solution pump to HP and LP generator for concentration. Heat generated is carried to atmosphere by cooling water. This process is continued, and refrigeration effect is repeated.

Absorption Chiller Principle

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Absorption chiller occupies vital position in an HVAC system. Absorption chiller is an equipment which uses a heat source, a refrigerant and an absorbent for producing chilled or hot water. In the types of chillers,along with vapor compression water chiller or electric chiller, absorption cooling system is also used in many applications. Absorption chillers produce chilled water under vacuum conditions for the purpose of air-conditioning and technology process.

Basic components of Vapor absorption chillers

Absorption chillers in its simplest form (single stage) consist of following main parts:

  • Generator
  • Condenser
  • Evaporator
  • Absorber
  • Heat exchanger
  • Refrigerant Pump
  • Solution pump

Working Principle of Absorption Chiller

1. Function of Generator in absorption chiller

In generator of absorption chillers weak solution is heated by operating steam (steam absorption chillers),hot water or flue gases in indirect fired absorption chillers.While direct fired absorption chillers are Natural gas, Diesel or Kerosene Oil Operated.After heating in generator solution is concentrated and high temperature refrigerant vapors are produced.After generator process in a chiller high temperature and pressure refrigerant vapors travel to condenser. A strong solution enters absorber through heat exchanger in exchanging heat with weak solution .

2. Function of Condenser  in absorption chiller

vapor absorption cycle in HVAC

Refrigerant vapor from generator is condensed in condenser by cooling water. Condensation is constant pressure process where refrigerant (water) gives off its heat to cooling water .In this way refrigerant heat is carried to atmosphere.In water cooled chillers, cooling water recycles after exchanging heat with air in cooling towers of same HVAC system.

3. Function of Evaporator in absorption chiller

Refrigerant from condenser flows to evaporator .In this compartment of absorption chiller,refrigerant gets vaporized by taking heat from chilled water.Refrigerant from evaporator refrigerant pan is pumped over the evaporator tubes with the help of refrigerant pump.Flow of refrigerant over evaporator tubes evaporates the refrigerant thus producing refrigeration effect, and evaporates to form vapor by absorbing heat of chilled water flowing through tubes.In this way,evaporation takes place at constant pressure process where refrigerant gets latent heat from chiller water. Chiller absorption takes place here in absorber. Chilled water is cooled and return to the system of customer.

4. Function of Absorber in absorption chiller

Absorber in absorption chiller

Produced refrigerant vapor enters absorber, and absorbed by strong solution in the absorber. In this way,strong solution is diluted by absorbing refrigerant vapor in absorber . Heat generated is carried to atmosphere by cooling water.

5. Function of HVAC Solution Pump in absorption chiller

This weak solution is transferred by solution pump to generator for concentration.Pumps are components in absorption cooling systems which require electric energy for its operation.Weak solution from the absorber is pumped into the generator through heat exchanger. This process is continued, and refrigeration effect is repeated.

HVAC Water Chillers Principle

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Water chillers are spine of HVAC cooling methods.Water chiller is a refrigeration machine which produces chilled water ( Approx 7 Diploma C ~ 12 Diploma C).The first operate of a chiller is to decrease the temperature of water to such worth such that it may be used for producing cooling impact in integration with different HVAC parts. A water chiller is rather like a different fridge machine however as an alternative of conserving your meals cool or making ice,it produces chilled water.The output of chiller is a water at decrease temperature often round about 10 degC relying upon the Chiller design.

HVAC water chillers play important function in any HVAC methods together with different primary parts. Chillers have gotten a lot consideration in recent times for its new designs and efficiency enchancment in current designs. New designs have resulted inhvac chiller with higher effectivity and fewer operation and upkeep prices. One other fascinating options is power saving and exact load or capability management  for brand new chillers. We see the chillers with above options in market however as engineering professionals we hope to see extra with design enhancements with much less O & M value. It’s important a part of HVAC system to have a chiller. Chiller producers have additionally expanded their manufacturing as properly design capabilities to cater to the diversified calls for of  HVAC chillers.

HVAC Chiller Fundamentals 

Working Precept of Vapor Compression Chiller

An HVAC chiller works on vapor compression or vapor absorption cycle.In vapor compression cycle, refrigerant circulates in evaporator ,compressor, condenser and enlargement valve of a chiller. A thermodynamic course of happens in every of above chillers.Theoretical working of Vapor compression or compression chillers is defined under.

Working Principle of Water Chillers

Warmth addition to refrigerant in evaporator ( 1-2) :

Refrigerant will get vaporized by taking warmth from chilled water in evaporator thus serving its prime objective. Refrigerant comes out of evaporator as vapors however on different facet chilled water is produced. Thus warmth is added to refrigerant at fixed strain however is extracted from chilled water. Each refrigerant and chilled water don’t get combined and are separated by some stable wall in between them in evaporator like shell and tube design.

Compression of refrigerant vapors in compressor (2 – three ) :

Refrigerant vapors come out of evaporator after which compressed by chiller compressor to excessive stress and temperature. Compressor requires vitality enter for its working and therefore electrical vitality is equipped to it.

Warmth rejection by refrigerant in condenser ( three – four ) :

Much like evaporator ,however reverse is occurring right here. Refrigerant rejects its warmth to outdoors cooling liquid or air .On this manner, refrigerant will get condensed and out of doors media is heated. outdoors media e.g. cooling water could also be cooled by cooling tower and recycled once more into condenser.

Enlargement of refrigerant in enlargement valve ( four -1 ) :

Refrigerant in condensed type popping out of condenser is expanded in enlargement valve and its stress and temperature is diminished to stage of evaporator in order that above cycle is repeated once more.

In above 4 parts of HVAC chiller, evaporator is the half the place we get chilled water after exchanging warmth with refrigerant.

HVAC Valves

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HVAC Valves are such parts with out which we can’t management movement in pipes .Valves are wanted for each media whether or not it’s water, gasoline, air or some other liquid. Valves would have been wanted for solids if they might have potential to circulate. Like different areas, valves discover its intensive use in HVAC (heating, air flow and air-conditioning).

With particular deal with HVAC, following are the some main HVAC utility of valves.

  • Water Chiller, the center of HVAC system, has valves on inlet and outlet traces of chilled water and cooling water. These valves are often gate and globe valves that are used for isolation and throttling functions. Water chiller operates on vapor compression cycle or vapor absorption cycles which additionally require valves internally as a requirement of thermodynamics. For instance Refrigerant growth valve is required inside a water chiller cycle. Chilled and cooling water headers additionally want valves for isolation and heating/cooling changeover.
  • Much like water chillers, HVAC scorching water generator has additionally valves on its inlet and outlet for isolation and circulation management functions. If water chiller also can act as water heater then there is no such thing as a want of sizzling water generator clearly.
  • Chilled water pumps and cooling water pumps have additionally isolation and throttling valves on their inlets and retailers. Once we discuss water pumps then there are additionally test valves on the outlet of pumps to forestall reverse circulation.
  • Cooling towers are one other hvac equipments which require valves at inlet and outlet for stream management of cooling waterGenerally a float valve can also be within the basin of cooling tower to regulate the extent of water in cooling streams. Valves would even be wanted for make-up water traces in HVAC system and cooling towers.
  • Air dealing with models (AHUs) additionally want valves at inlet and outlet to control chilled water as per demand of cooling within the areas relying upon the kind of HVAC management system. These air dealing with unit valves are additionally related to some HVAC software program to remotely function them as per cooling/heating demand from HVAC customers. Drain valves are additionally provisioned inside air dealing with models.
  • If Fan Coil Items (FCUs) are put in in particular person rooms then valves may even be put in at entry and exit of those models to have exact management of cooling /heating for occupants of that house.

Recommendations to HVAC Engineers

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As HVAC system engineer, one has to regulate all elements and areas that may lower the effectivity of system or enhance downtime or HVAC system unavailability or enhance the upkeep value of heating, air flow and air-conditioning system. The accountability begins from very starting, once you determine to put in HVAC system and begin engaged on it in any means.

Following are the ideas for clean, bother free and economical operation/working of hvac system.

  1. Begin your working from the very early levels of hvac system choice, procurement and tendering. Don’t ignore all these pre-installation steps as it will grow to be troublesome at later phases to change any pre-done work. Full your house work in collection of sort of chillers you will set up in your constructing or area or for different functions. Seek the advice of HVAC specialists for getting execs and cons of various kinds of chillers and choose the one which fits your sources and priorities. Then choose the famend and dependable producer for buying the hvac system elements. Get entangled in tenders to make sure transparency in entire course of.
  2. HVAC Set up is essential section for hvac engineers. Embrace all important objects and equipment in hvac contract BOQ and monitor the actions of HVAC contactor so that each one goes in accordance with boq or phrases and circumstances written whereas awarding contract. Be certain that all set up is carried out in accordance with drawings and all elements meet the specs talked about in BOQ. Your saving at any stage could lead on you to spend extra in later levels. By no means compromise the fabric of all gadgets being put in in HVAC system. Low high quality materials would lastly take you to issues in coming days/years. Commissioning is as necessary as its set up so adhere to commissioning procedures always and don’t ignore any factor in courtesy.
  3. Coaching of hvac personnel is essential in operation and upkeep standpoint. So embody coaching of your personnel in contract or organize it individually. Your expenditure on manpower coaching would pay again you in future so by no means overlook it.
  4. Put together all hvac procedures associated to operation and upkeep of every element of hvac system and implement it strictly. Adhere to upkeep program in your water chillers, air dealing with items, cooling towers and fan coil models .Your adherence to upkeep packages would by no means allow you to face any drawback relating to the unavailability of hvac system. At all times attempt to full upkeep work well timed in the very best obtainable sources or with the help of hvac provider
  5. Undertake hvac pro-active method concerning important and warmth switch interfaces/surfaces or to function HVAC system at most effectivity, give attention to warmth switch interfaces/surfaces. On this regard condenser is most necessary, preserve it at optimum circumstances. Scaling, corrosion and excessive stress in condenser would get you in bother lastly so be pro-active earlier than your condenser enables you to down. Heating and cooling coils are additionally equally essential as these would immediately have an effect on cooling or heating in hvac areas/zones. Get all coils cleaned and hold them in finest warmth switch situation. Guarantee well timed upkeep of cooling towers to function them at most effectivity/effectiveness.

Classification of HVAC Chillers

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Classification of HVAC chillers

Chiller Varieties have been designed to cater to the diversified requirement of commercial chillers. Water chillers have advanced because of the selection in availability of sort of power at business or small degree.

Sorts of chillers have made the usage of the chillers versatile by way of power enter.

HVAC Chiller

Industrial analysis within the subject of chiller has eased the number of chillers in a cost-effective and sturdy method.There isn’t a want of fear no matter sort of vitality you’ve out there with you.

Every sort of chiller targets the precise customers categorized on the idea of sort of vitality they’ve.

HVAC programs make use of various kinds of chillers inside the obtainable assets of shoppers or customers.

A chiller could also be the most suitable choice for explicit software whereas the identical chiller might expensive or much less possible for an additional utility or plant.

HVAC water chillers are labeled totally on the idea of cycle on which they work.

  • Vapor compression chillers or compression chillers or electrical chillers
  • Vapor absorption chillers or absorption chillers or ammonia chillers or lithium bromide chillers

Classification of HVAC chillers


Vapor compression chillers are additional categorized on following foundation.

  • Kind of compressor i.e reciprocating compressor,rotory compressor or screw compressor kind vapor compressor chillers
  • Sort of condenser i.e air cooled condenser or air cooled chillers OR water cooled condensers or water cooled chillers

Whereas Vapor absorption chillers are additional categorised as following:

  • Direct fired absorption chillers (Pure gasoline, Diesel or Kerosene Oil Operated)
  • Oblique fired absorption chillers