BENEFITS OF AIR CONDITIONERS, AIR PURIFIERS AND VENTILATION SYSTEMS FOR HOSPITALS

Hospital Air Conditioning is more important because these days proper air conditioning has also become a factor in patient therapy and in some cases controlled environment provides more rapid physical improvement as the growth of many disease causing organisms is influenced by the surrounding temperature. Hence, proper air conditioning is found to play an important role in the prevention and treatment of diseases. Apart from controlled temperature, indoor air quality in the hospitals should also be maintained at the acceptable levels because there are large number of bacteria and virus spread in the hospital environment. Air purifiers and proper ventilation system help in improving the indoor air quality.

The benefits of having proper air Conditioning System, air purifiers and ventilation systems in the hospitals are:

Air conditioning system restricts the movement of air between the various departments of the hospital.

Ventilation and filtration helps in the dilution and removal of contaminants, which are in the form of airborne microorganisms, viruses, odor, hazardous chemicals and radioactive substances.

Air conditioners provide different types of temperature and humidity required for various areas in the hospital.

All the above systems help in controlling the environmental conditions, quality and circulation of the air.

Patients with some diseases such as thyrotoxicosis, cannot tolerate hot and humid conditions, in such cases, a cool and dry environment favors the loss of heat by radiation and skin evaporation which may save the life of a patient.

In some cases dry conditions may prove hazardous to the ill and debilitated persons, contributing to secondary infection. In such cases, AC is helpful in preventing these dry conditions.

It also reduces operational costs and maintenance costs for a hospital.

Designing of an energy efficient air conditioning system by a hospital according to its needs and best Hospital operating theatres, in which air is filtered to high levels to reduce infection risk and the humidity controlled to limit patient dehydration. Although temperatures are often in the comfort range, some specialist procedures such as open heart surgery require low temperatures (about 18 °C, 64 °F) and others such as neonatal relatively high temperatures (about 28 °C, 82 °F).international practices, delivers a high quality product that is heath safe.

FILTERATION

All air supply to hospitals is filtered. Filtration, as other specifications, is dictated by codes and standards. General use areas have enough filtration to eliminate from the air particulate matter that could cause maintenance problems with components of the air supply system or general cleaning problems, and to eliminate it from the intake of animal life.

Air can be filtered at the intake and/or along the path to delivery to rooms in the building OR probably will be supplied with air that is filtered first at the outside air intake and then again as it enters the main duct in the air handler. The efficiency of the second stage of filtering will be higher than that of the first stage and thus will filter out smaller contaminants. For some rooms, final filtering at the duct entering the room might be required. These are special use rooms for clean room applications, for some types of surgical procedures, or to protect some kinds of patients who are extraordinarily susceptible to infection.

Filter testing and maintenance are typically based upon the measured differential pressure across the filter. With a known air flow rate, the resistance of the filter can be calculated based upon the area of the filter and the flow. Manufacturers of filters will specify a range of resistance or pressure differentials that constitute a normal range of operation. Higher resistances indicate occlusion of the filter, lower resistances, breaches in the filter, or leaks in or around the filter. Testing of “filter drop” using differential pressure gauges can be performed with handheld equipment, stationary monitoring meters, or remote monitoring and alarm systems. Handling of some exhaust filters requires special precautions, including filters from isolation rooms and from chemical and biological exhaust hoods.

Filtration helps in the dilution and removal of contaminants, which are in the form of airborne microorganisms, viruses, odor, hazardous chemicals and radioactive substances. Rooms that house patients with infectious diseases (e.g., tuberculosis) will be designed to prevent airborne pathogens from leaving the room and entering the hospital’s general air circulation. Such rooms are kept at a negative pressure relationship to the hall and adjacent areas. This is accomplished by exhausting more air than is supplied, it include high-efficiency filtration of exhaust air to reduce the possibility of contaminating outside air in the vicinity of other air intakes.

AIR CHANGES & STERILITY OF AIR

Codes and standards usually dictate the required amount of air to be supplied and exhausted into any room or area of a hospital. These will vary according to the use of the space. The design parameter is expressed in “room air changes per hour.” Knowing the room volume allows the designer to specify a volume of air to be supplied (in cubic feet per minute (CFM) for a room that might be divided among several duct outlets or vents in the room. The pressure relationship of each room, with respect to adjacent spaces, likewise probably will be dictated by codes or

standards. Some medical circumstances require special ventilation. “Isolation” rooms might have a specific code definition and requirements. In general terms, there are needs to prevent air from entering a room or, in some cases, from leaving a room. Patient rooms housing transplant patients with suppressed immune systems need to minimize the possibility of contamination from airborne pathogens that may be found in the hospital but at levels not harmful to a healthy individual. These rooms are typically maintained at positive pressure relative to the hallway and adjacent spaces and might include a two-door isolation system with an intervening space between the hall and the room. In this configuration, the room is positively pressurized with respect to the intervening space and the hallway so that air tends to flow out of the room, rather than into it through an open door. This pressure relationship is established by supplying more air to the room than is exhausted. Testing and monitoring such conditions can be accomplished by using differential pressure measuring systems with alarms or can be confirmed by using smoke to visualize the actual flow of air at the door when it is opened. More sophisticated testing can be performed using trace amounts of elements tagged to the ventilation air and can be monitored with specific detectors.

Rooms that house patients with infectious diseases (e.g., tuberculosis) will be designed to prevent airborne pathogens from leaving the room and entering the hospital’s general air circulation. Such rooms are kept at a negative pressure relationship to the hall and adjacent areas. This is accomplished by exhausting more air than is supplied, it and can include high-efficiency filtration of exhaust air to reduce the possibility of contaminating outside air in the vicinity of other air intakes.

An office space requires the minimum amount of air exchanges per hour and is neutral in pressure with respect to adjacent spaces. An operating room requires greater air exchange rates and might have an unbalanced supply-to-exhaust relationship. Special cases for isolation rooms, clean rooms, and other applications sometimes exist. Systems can be as simple as a fan running at a fixed speed for supply and exhaust with ducts . More complicated systems might have variable air volume (VAV) schemes that use variable speed motors to drive fans or variable aperture vents at the end of the ductwork supplying each area. Another variation of controls incorporates a constant volume vent at the end of the supply duct to compensate for any changes in pressure elsewhere in the ventilation system.

In many designs, return air systems are included, rather than simple exhaust systems. A forced air furnace for a home probably has a single fan that draws air from the house and blows it though a heating chamber and then back into the house. Return-air systems for hospitals function in a similar way but use separate fans to remove air from the building and return it to the intake of the supply fan, where some part of the returned air is exhausted to the atmosphere, and the difference is made up of fresh outside air. Again, codes and standards will dictate the minimum percentage of outside air that must be supplied to the building. Return air systems are used to conserve energy for either cooling or heating. Imagine, for example, that the outside air temperature is 30°F. This air is heated handler and is then supplied to rooms in the building,

where it may be heated even more to achieve a desired room temperature. In a system that uses 100% outside air for supply, the energy cost of heating the air would be higher than that of a return air system that used 20% outside air and 80% return air since the returned air already would be at or near the target room air temperature and would not need to be heated. Using a variable percentage of outside air (versus returned air) through control of dampers is known as an “economizer cycle”. Economizer control routines might be simple and controlled at the air handler or might be part of a larger building automation and energy management system.

DEODORIZATION AIR-CONDITIONING SYSTEM

A comfortable hospital environment has a positive impact on a patient's recovery from disease. It also helps to improve the overall working conditions& Delivering a comfortable hospital environment

In a hospital, which generates a variety of unclean wastes, many healthcare workers including doctors and nurses are likely to be concerned by malodors. The deodorization can be of two types:

ELECTRONIC AIR CLEANERS: Electronic air purification systems achieve their air cleansing and deodorizing effect by filtering air through an electrically charged grid or scrubber. When larger airborne microorganisms (pollen, some fungi) pass through the electrically charged filtration system, they are, quite literally, burned up. Smaller microorganisms and VOCs may be filtered from air by fine mesh and activated charcoal filters or sorbents. The option to purchase and install such a system is usually in the hands of the structure owner and, therefore, is not commonly a technique used by professional deodorizing contractors.

OZONE GENERATION: Ozone is an unstable combination of three atoms of oxygen. It is formed by exciting molecular oxygen (O2) into atomic oxygen (O, or single atoms) in an energized environment that allows the recombining of three oxygen atoms to form ozone (O3). Generally, ozone is known to be a more effective bactericide, fungicide and virucide than chlorine compounds. In many European countries, ozone, rather than chlorine, is the primary agent for water purification. This applies to drinking water as well as to water used in pools and spas where human consumption or contact is anticipated.

Because of the instability of gaseous ozone, it cannot be generated and stored for later use. Consequently, ozone needs to be generated on-site for deodorization, disinfection and even sterilization purposes. Ozone effectively and permanently destroys odor through oxidation. When ozone comes in contact with an organic odor or odor-causing microorganism, the extra atom of oxygen is imparted and oxidation of the odor (chemical "burning" in layman's terms) takes place. The result of the oxidation reaction is a little moisture (H2O), a molecule of oxygen (O2) and some nitrogen dioxide (NO2).

Distributed Deodorization with Separate Units A distributed deodorization system with separate units delivers safe and highly efficient deodorization by combining a clean fan unit with a catalytic deodorization system. The system is suitable for a small-sized hospital or a renovation project. Depending on the conditions, it can be installed per room or per floor, and is available in three models: embedded-in-ceiling, cassette-on-ceiling, and vertical models.

Centralized Deodorization Air-Conditioning: A centralized deodorization system converts a central air system into a safe and highly efficient deodorization system. Since it is centralized, it can be easily managed and is suitable for a large hospital. The deodorization system can also be installed into an existing air-conditioning system. In addition, with a built-in optional unit for the air conditioner installed it can be used as a sterilizer.

Clean fan unit equipped with a deodorizing catalyst

Different types of Distributed Deodorization with Separate Units

Centralized Deodorization System

DEHUMIDIFICATION AIR-CONDITIONING SYSTEM FOR HOSPITALS

Importance of Dehumidifiers

Dehumidifiers are the appliances that are used to extract the moisture and to reduce the humidity level in the air. Humidity level mainly arises in rainy season when large amount of rain fall is experienced. At this time, our air conditioners are not able to reduce the humidity level from all portions of rooms.

Due to the moisture present in air, hospital room gets damp and results in the formation of molds, fleas and etc. The formation of molds may cause health risks and they can destroy anything that comes in their contact.

At this stage dehumidifier is used to extract the excess moisture from air and to provide a comfort environment. Dehumidifiers can protect hospital environment from molds and humidity in almost every season whether it is summer, winter or heavy rainfall.

Moisture in the air can cause many health problems, ranging from mold allergy to respiratory illnesses. These are particularly dangerous to those who suffer from asthma, bronchitis, or allergies. Dehumidifiers work by reducing the amount of moisture that is in the immediate environment. This prohibits the amount of mold that is allowed to grow and is one of the most preferred methods for removing moisture or humidity from a room. Using the process of condensation, dehumidifiers take the moisture from a room and pass it over a cool surface, such as coils. The moisture that is in the air cannot remain once the air is cool and it liquefies and drips. You can view the same process of condensation anytime you have a cold drink in a glass

kept in a warm room. When the moisture in the air hits the cool glass, beads of water will begin to form on the glass’ surface. If you leave the glass sitting for any length of time and then pick it up you’ll notice that there is a little pool or puddle of water where the glass was sitting. This is the same concept of a dehumidifier.

Dehumidifiers, like the cold glass, collect the moisture from the air and collect it as it pools. Therefore, it is important to pay close attention to how you will handle the water that needs to be removed from the dehumidifier. Many dehumidifiers have tanks that will hold a specific amount of water, so make sure to choose a unit that will best meet hospital’s needs. It’s also important to choose a dehumidifier that will effectively handle the amount of moisture in your room.

Dehumidifiers can be used as standalone units. Dehumidifier has following components:

Components

Normally Dehumidifiers have a cooling system made up of these primary components:

The compressor is the quiet motor (engine) of the cooling system. It's the black, football-size component at the bottom of your dehumidifier. The compressor runs as long as the dehumidifier humidistat (the humidity-sensor) calls for a reduction in the humidity.

The condenser is a series of finned tubes, similar to a radiator. It's usually near the circulating fan.

The evaporator is located near the back of the dehumidifier, right above the water-collection container. It also resembles a radiator or a coiled-up set of tubes. When the dehumidifier's humidistat senses increased humidity, it cycles on, which starts the compressor and circulating fan.

The circulating fan circulates the air over the evaporator and condenser coils.

Principal of operation: When the unit runs, the circulating fan and compressor also run. The fan continually draws room air over the evaporator coils, which are cold, and then over the condenser coils, which are warm. Because the evaporator coils are cold, the moisture in the room collects on them--just as the outside of a glass of icy liquid "sweats" on a warm, humid day. When the moisture on the coils increases, it drips off of the coils into the collection container.

The air then flows over the warm condenser coils and out into the room. This process removes water from the air and, because of the heat from the fan motor and compressor motor, the exiting air is somewhat warmer, as well as dryer.

Air-conditioning facilities in hospitals are considered to be a cause of hospital infection, as they are constantly exposed to humidity. Such humidity may condense into a breeding ground for fungi and bacteria, being spread throughout the hospital via air-conditioning ductwork and indoor facilities.

Hygienic hospital spaces can also be created using an air-conditioning system with dehumidification capabilities in the duct and fan coil units. Furthermore, by utilizing waste heat derived from the cold source for the air conditioning and from cogeneration, it also promotes energy savings. Using a dehumidification system in the outside-air intake unit is: Preventing breeding and the spread of fungi and bacteria with dry operation & Energy saving through utilization of cooling water, Utilizing waste heat from a cold source for air conditioning.

It provide large energy-savings by utilizing waste heat from a cold source for air conditioning and from cogeneration, and utilizing the recovered heat as a re-heating heat source for the outside-air dehumidification system. So for humidifiers can be used as standalone as well as integration with air conditioning system.

CRYOGENIC SYSTEMS

In physics, cryogenics is the study of the production of very low temperature (below −150 °C, −238 °F or 123 K) and the behavior of materials at those temperatures. So cryogenic systems are those which produce very low temperature. Liquefied gases, such as liquid nitrogen and liquid helium, are used in many cryogenic applications. Liquid nitrogen is the most commonly used element in cryogenics and is legally purchasable around the world. Liquid helium is also commonly used and allows for the lowest attainable temperatures to be reached. These liquids are held in either special containers known as Dewar flasks, which are generally about six feet tall (1.8 m) and three feet (91.5 cm) in diameter, or giant tanks in larger commercial operations. Dewar flasks are named after their inventor, James Dewar, the man who first liquefied hydrogen. Cryogenic cooling of devices and material is usually achieved via the use of liquid nitrogen, liquid helium, or a cryocompressor (which uses high pressure helium lines). Newer devices such as pulse cryocoolers and Stirling cryocoolers have been devised.

Liquid Nitrogen: Liquid nitrogen is nitrogen in liquid state at a very low temperature. It is produced industrially by fractional distillation of liquid air. Liquid nitrogen is a colourless, clear liquid & is often referred to by the abbreviation, LN2 or "LIN" or "LN".

At atmospheric pressure, liquid nitrogen boils at 77K (-196°C; -321°F) and is a cryogenic fluid which can cause rapid freezing on contact with living tissue, which may lead to frostbite. When appropriately insulated from ambient heat, liquid nitrogen can be stored and transported, for example in vacuum flasks. Here, the very low temperature is held constant at 77 K by slow boiling of the liquid, resulting in the evolution of nitrogen gas. Depending on the size and design, the holding time of vacuum flasks ranges from a few hours to a few weeks.

Liquid nitrogen freezes at 63 K (−210 °C; −346 °F). Despite its reputation, liquid nitrogen's efficiency as a coolant is limited by the fact that it boils immediately on contact with a warmer object, enveloping the object in insulating nitrogen gas. This effect, known as the Leiden frost effect, applies to any liquid in contact with an object significantly hotter than its boiling point.

Liquid nitrogen is a compact and readily transported source of nitrogen gas without pressurization. Further, its ability to maintain temperatures far below the freezing point of water makes it extremely useful in a wide range of applications, primarily as an open-cycle refrigerant, including:

As a coolant for CCD cameras in astronomy To store cells at low temperature for laboratory work For the immersion freezing and transportation of food products For the cryopreservation of blood, reproductive cells (sperm and egg), and other

biological samples and materials As a method of freezing water pipes in order to work on them in situations where a valve

is not available to block water flow to the work area In the process of promession, a way to dispose of the dead For cooling a high-temperature superconductor to a temperature sufficient to achieve

superconductivity For the cryonic preservation in the hope of future reanimation. To preserve tissue samples from surgical excisions for future studies To shrink-weld machinery parts together As a coolant for computers. In food preparation, such as for making ultra-smooth ice cream

Some applications of cryogenics:

Magnetic Resonance Imaging (MRI)

MRI is a method of imaging objects that uses a strong magnetic field to detect the relaxation of protons that have been perturbed by a radio-frequency pulse. This magnetic field is generated by electromagnets, and high field strengths can be achieved by using superconducting magnets. Traditionally, liquid helium is used to cool the coils because it has a boiling point of around 4 K at ambient pressure, and cheap metallic superconductors can be used for the coil wiring. So-called high-temperature superconducting compounds can be made to superconductors with the use of liquid nitrogen which boils at around 77 K.

Electric power transmission in big cities

It is difficult to transmit power by overhead cables in big cities, so underground cables are used. But underground cables get heated and the resistance of the wire increases leading to wastage of power. This can be solved by cryogenics. Liquefied gases are sprayed on the cables to keep them cool and reduce their resistance [citation needed].

Frozen food

Cryogenic gases are used in transportation of large masses of frozen food. When very large quantities of food must be transported to regions like war fields, earthquake hit regions, etc., they must be stored for a long time, so cryogenic food freezing is used. Cryogenic food freezing is also helpful for large scale food processing industries.

Blood banking

Certain blood groups which are rare are stored at low temperatures, such as -165 degrees C.

MEDICAL GAS SUPPLY

Medical gas systems in hospitals, and most other healthcare facilities, are essential for supplying oxygen, nitrous oxide, nitrogen, carbon dioxide and medical air to various parts of the hospital. These systems are usually highly monitored by various alarm systems. Following are the main constituents of medical gas supply:

Oxygen: Oxygen may be used for patients requiring supplemental oxygen via a mask. Usually accomplished by a large storage system of liquid oxygen at the hospital which is evaporated into a concentrated oxygen supply, pressures are usually around 55 psi. In small medical centers with a low patient capacity, oxygen is usually supplied by multiple standard cylinders.

Nitrous Oxide: Nitrous Oxide is supplied to various surgical suites for its anesthetic functions during pre-operative procedures. Delivered to the hospital in standard tanks and supplied through the Medical Gas system. System pressures around 50 psi.

Nitrogen: Nitrogen is typically used to power surgical equipment during various procedures. Pressures range around 175 psi to the various locations.

Carbon Dioxide: Typically used to inflate or suspend tissues during surgery. System pressures are maintained at about 50 psi. it is also used in laser surgeries.

Medical Air: Medical Air is supplied by a special air compressor to patient care areas using clean outside air. Pressures are maintained around 55 psi.

Medical Vacuum: Medical Vacuum in a hospital supports vacuum equipment and evacuation procedures, usually supplied by various vacuum pump systems exhausting to the atmosphere.

Medical gas supply takes the form of either cylinders or a piped gas system, depending on the requirements of the hospital.

Cylinders:

Components

1. Cylinders are made of thin walled seamless molybdenum steel in which gases and vapours are stored under pressure. They are designed to withstand considerable internal pressure.

2. The top end of the cylinder is called the neck, and this ends in a tapered screw thread into which the valve is fitted. The thread is sealed with a material that melts if the cylinder is exposed to intense heat. This allows the gas to escape so reducing the risk of an explosion.

3. There is a plastic disc around the neck of the cylinder. The year when the cylinder was last examined can be identified from the shape and colour of the disc.

4. Cylinders are manufactured in different sizes (A to J). Sizes A and H are not used for medical gases. Cylinders attached to the anaesthetic machine are usually size E , while size J cylinders are commonly used for cylinder manifolds. Size E oxygen cylinder contains 680 litres, whereas size E nitrous oxide can release 1800 litres. The smallest sized cylinder, size C, can hold 1.2 litres of water while the largest, L, can hold 50 litres.

5. Lightweight cylinders can be made from aluminium alloy with a fibreglass covering in epoxy resin matrix. These can be used to provide oxygen at home or during transport. They have a flat base to help in storage and handling.

Problems in practice and safety features

1. The gases and vapours should be free of water vapour when stored in cylinders. Water vapour freezes and blocks the exit port when the temperature of the cylinder decreases on opening.

2. The outlet valve uses the pin index system to make it almost impossible to connect a cylinder to the wrong yoke.

3. Cylinders are colour-coded to reduce accidental use of the wrong gas or vapour.

4. Cylinders should be checked regularly whilst in use to ensure that they have sufficient content and that leaks do not occur.

5. Cylinders should be stored in a purpose built dry, well-ventilated and fireproof room, preferably inside and not subjected to extremes of heat. They should not be stored near flammable materials such as oil or grease or near any source of heat. They should not be exposed to continuous dampness, corrosive chemicals or fumes. This can lead to corrosion of cylinders and their valves.

6. To avoid accidents, full cylinders should be stored separately from empty ones. F, G and J size cylinders are stored upright to avoid damage to the valves. C, D and E size cylinders can be stored horizontally on shelves made of a material that does not damage the surface of the cylinders.

7. Over pressurized cylinders are hazardous and should be reported to the manufacturer.

Centralized (Piped) gas supply

It is a system where gases are delivered from central supply points to different sites in the hospital at a pressure of about 400 kPa. Special outlet valves supply the various needs throughout the hospital.Oxygen, nitrous oxide, compressed air and medical vacuum are commonly supplied through the pipeline system.

Components

1. Central supply points such as cylinder banks or liquid oxygen storage tank.

2. Pipe work made of special high quality copper alloy, which both prevents degradation of the gases it contains and has bacteriostatic properties. The fittings used are made from brass and are brazed rather than soldered.

3. The size of the pipes differs according to the demand that they carry. Pipes with a 42 mm diameter are usually used for leaving the manifold. Smaller diameter tubes, such as 15 mm, are used after repeated branching.

4. Outlets which are identified by gas colour-coding, gas name. They accept matching quick connect/ disconnect probes, Schrader sockets, with an indexing collar specific for each gas (or gas mixture).

5. Outlets can be installed as flush fitting units, surface-fitting units, on booms or pendants, suspended on a hose and gang mounted.

6. Flexible colour-coded hoses connect the outlets to the anaesthetic machine. The anaesthetic machine end should be permanently fixed using a nut and liner union where the thread is gas specific and non interchangeable (non-interchangeable screw thread, NIST is the British Standard).

7. Isolating valves behind break glass covers are positioned at strategic points throughout the pipeline network. They are also known as AVSUs (Area Valve Service Units).

Fig: Example of centralized supply of Liquid Oxygen

Problems in practice and safety features:

A reserve bank of cylinders is available should the primary supply fail. Low pressure alarms detect gas supply failure.

Single hose test is performed to detect cross-connection. Tug test is performed to detect misconnection. Regulations for installation, repair and modification are enforced. Anaesthetists are responsible for the gases supplied from the terminal outlet through to

the anaesthetic machine. Pharmacy, Supplies and Engineering departments share the responsibility for the gas pipelines ‘behind the wall’.

There is the risk of fire from worn or damaged hoses that are designed to carry gases under pressure from a primary source such as a cylinder or wall mounted terminal to medical devices such as ventilators and anaesthetic machines. Because of heavy wear and tear, the risk of rupture is greatest in oxygen hoses used with transport devices. Regular inspection and replacement, every 2–5 years, of all medical gas hoses is recommended.

PRINCIPAL OF PRODUCTION OF LIQUID OXYGEN

For the Production of liquid oxygen we use air. The air we breath is actually a mixture of gases, roughly 78% nitrogen (N2), 21% oxygen (O2), 1% Argon (Ar), 0.5% water vapor (H2O), 0.2% carbon dioxide (CO2) and 0.2% methane (CH4). In order for oxygen to be separated from air in liquid form, conditions must be "cryogenic" (i.e., at temperatures below -150 degrees Celsius). At these temperatures, however, H20, carbon dioxide, methane and other hydrocarbons present in trace amounts will turn to solids, potentially blocking the distillation equipment. Therefore, the liquid oxygen collection process begins by filtering out impurities (i.e., any molecules other than N2, O2 and Ar).

Removing Impurities

Air taken from the outside environment is compressed to six times atmospheric pressure (6 atm) and allowed to slowly escape into a series of larger containers one at a time. Following basic gas laws, this gradual expansion of air (decreasing pressure and increasing volume) causes the air's temperature to drop. This temperature drop causes the water vapor to condense into liquid water, thus separating it from the gaseous air. Once dehydrated, the air is compressed and forced through a special polymer sieve that filters out carbon dioxide, hydrocarbons (methane, hexane, etc.) and any trace water vapor.

Fractional Distillation

Nitrogen, oxygen and argon have distinct boiling points: the temperatures at which their state changes from gas to liquid. Nitrogen has the lowest (-195 degrees C), argon has the second lowest (-185 degrees C) and oxygen has the highest of the three (-183 degrees C). A complex and powerful process, the fractional distillation of air basically works by lowering air to

cryogenic temperatures between -183 C and -185 C, causing oxygen gas to condense on the lower walls of the compressor tank as liquid oxygen. Then still-gaseous nitrogen and argon are allowed to escape into openings at the top of the tank, leaving 99% pure liquid oxygen at the bottom.

How Does Cryogenic Freezing Work?

After being pressurized, purified air is injected into a single-stroke piston engine. When the piston is just starting the downward phase of its stroke cycle, the inlet valve opens and sprays highly-pressurized air into the piston chamber. This increases pressure in the chamber. When applied across the circular surface of the piston head, this pressure is converted into force being applied downward, rotating the flywheel. At the middle of the downward phase, the inlet valve spans shut and the outlet value opens. Accelerated by the force from gravity and inlet pressure, the flywheel is carrying momentum. This momentum carries the flywheel around its axis, taking the piston head down to its lowest point in the cycle. When gas expands against the piston, it is doing "work" (the product of force and time) and loses energy. As a result, the temperature of the gas decreases. As the piston begins the upward swing of its cycle, the outlet vale snaps open. The upward moving piston head pushes the cooled air out through this opening until the head reaches its highest point. Here, the outlet snaps shut and the cycle begins again. To compound this cooling effect, the cooled outlet air is recirculated through coiled tubes running through the inside of the original pressurized air source. The pressurized air loses heat to the cold tubes and decreases in temperature. This colder pressurized air gets colder still when it exits the expansion engine, which gets pushed into coiled tube, which cools the remaining pressurized air, ad infinitum.

How Is Liquid Oxygen Packaged?

Fractional distillation plants often won't package liquid oxygen themselves. Rather, long pipelines will transport it from the plant to end users who possess the machinery to fill aluminum or steel tanks with pressured liquid oxygen. These end users often different sizes of tank for different applications. Personal tanks (for hospitals, patient hand carts and emergency services) come in a wide variety of volumes, pressures and valve types. Commercial tanks (for laboratories, airplanes, mechanics, heavy manufacturing and other oxy-fuel welding applications) generally hold a volume between 40 and 48 liters at a pressure between 197 and 217 atm. For producers who do choose to package their own liquid oxygen for transport, they typically use trailer-sized tanks. This special cryogenic tanks feature two shells separated by a sealed vacuum (a style of container known as a "Dewar Glass"). With no gas molecules between the two layers, there is no across which heat can flow. These tanks can be transported by truck or rail.

Management of Fire Fighting

The hospital should have an organized fire, safety and disaster program under the direction and supervision of one or more persons qualified to implement the program.

Firefighting service

The chief executive officer, or his designee, should establish a workable plan with the nearest fire department for firefighting service. The hospital sould provide the fire department with a current floor plan of the building showing the location of firefighting equipment, exits, patient rooms, storage places of flammable and explosive gases, and other information as the fire department requires or as may be necessary.

Fire warning and safety systems

Every building should have an automatic and manually activated fire alarm system installed to transmit an alarm automatically to the fire department by the most direct and reliable method approved by local regulations.

Testing fire warning systems

Fire safety systems, including automatic fire extinguishing systems, automatic and manual alarms, stand-pipes, and hose reels should be of an approved type. They should be kept in good operating condition and inspected by qualified hospital personnel at least every 3 months.

Internal disaster and fire plans

The hospital should have an internal disaster and fire plan incorporating evacuation procedures. These plans should be made available to all personnel and posted throughout the hospital. These plans should be developed in accordance with the standards

Safety education program

All employes should participate in the safety program in the duties delegated to them and be instructed in the operation of the fire warning system, the proper use of firefighting equipment, and the procedure to follow in event that electric power is impaired.

SAFETY PRECAUTIONS

Emergency power: The emergency electric power source and associated equipment should be regularly inspected, tested and maintained in accordance with current Standards. A written record should be maintained of inspection, performance, exercising period and repairs of emergency power equipment.

Fire inspection: The hospital should request an annual inspection by its local fire department.

Smoking:

(a) The governing body should adopt written rules governing smoking within the hospital which shall be made known to hospital personnel, to patients and to the public.

(b) These rules should include at least the following:

Smoking should be prohibited in any room, ward or compartment where flammable liquid, combustible gas, or oxygen is being used or stored and in any other hazardous area of the hospital. The areas shall be posted with ‘‘NO SMOKING’’ signs.

Patients classified as not mentally or physically responsible for their actions shall be prohibited from smoking unless constant supervision is provided.

Hazardous areas

Special safety procedures, including use of special facilities and equipment, shall be provided for areas of the hospital which present an unusual hazard to patients and personnel. Exposed heating pipes and radiators in patient rooms and within reach shall be covered.

Electrical safety

All appliances, instruments and installations shall be tested before use to determine compliance with grounding, current leakage and other device safety requirements to ensure protection of patients and employees. A program of routine maintenance shall be effectively enforced to ensure that all electrical receptacles and plugs, wires and connectors are safe. If an appliance

requiring three-wire circuitry for grounding is attached to a two-wire outlet, the adaptor plug pigtail shall be attached to a ground.