Thursday, October 28, 2010

WE KNEW ABOUT VENTILATION

I have never failed to register my dislike of ‘small lofts’ particularly those mean and undersized structures which dictatorial, bureaucratized urban district councils sometimes permit their unfortunate tenants to erect in their back gardens. Believe it or not, these bureaucrats actually specify the size the loft is to be, yet they know nothing about racing pigeons or their permitted habitat nor about the hygiene without which animals cannot be kept as they should be. For instance, what do those form-filling bureaucrats know about ventilation and its affect on animals? Sweet Fanny Adams!

At the same time, what do fanciers know about ventilation and its effect on hygiene in the loft? I regret to have to say that the majority of fanciers have no idea at all! They think you can bung racing pigeons into any old shed, or disused barn, and then proceed to monopolize the prizes. Such thinking is so wide of the mark as to be laughable.

The first product of inadequate ventilation in a loft is the production of gases. What I want you all to understand is that gases have the facility of diffusion, a function which does not apply to everything.

It is in order for me to give you a further example, this time of non-diffusion. Let us help ourselves to a large glass jar and fill a third of its capacity with mercury, which is an extremely heavy metallic liquid. We now take up a can of water and pour this into the glass container until the liquid has taken up its third of the accommodation. Finally, we fill the remaining third of the glass jar with oil. So, we have oil, water and mercury stacked up inside the jar and wonder of wonders! Each liquid stays in its own space forbearing to mix with the other liquids in the jar. Even if we shake the contents of the glass jar in an attempt to make the contents diffuse, the three elements sort themselves out and stratarise with a third of the jar occupied by the mercury at the bottom, then the water, and finally the oil occupying a layer on top of the water. So, we have demonstrated the fact that certain elements won’t diffuse or, to put it another way, they won’t mix, representing a perfect case of class distinction!

Let us carry out another experiment which is as simple and informative as the non-diffusion demonstration. Once again we help ourselves to a capacious glass jar and into ft we pour a comparatively heavy gas, such as oxygen. Next, we pour into this jar a light gas, such as hydrogen. Right, we have two gases corked up in the Jar, a heavy one and a light one, and we leave them alone for a while. Soon, by chemical examination (because we cant see these gases which are invisible) we test the contents of the jar to discover if the two gases we put in it are infact not still separate and we find that the two gases had, in fact, diffused (mixed). This mixture would be the same throughout the jar, a perfect mixture of the two gases. This property (the mixing together of several gases) has a considerable bearing on ventilation, as we shall see. In fact, we have seen that one gas, which is sixteen times heavier than the other, has diffused with ft without difficulty!

Let us now tackle the aspect of loft ventilation by using the owner as a guinea pig. So, you are sitting in the corner of a room which has been sealed up, with you inside. You are breathing, of course, taking in air and exhaling carbonic acid gas. Although you are using up the air and replacing it with a poisonous gas, the latter gas does not work on you at once to affect your inhalement of air. This is because the carbonic acid gas you exhale from your lungs tends to diffuse with the air in the room, mixing freely with it. This process could continue for a long time before breathing became difficult or laboured because the air in the whole room would not deteriorate to a state where it affected breathing until the foul air given off by the lungs had practically exhausted the oxygen content of the gases.

We know, because we were taught at school, that air expands with heat and contracts with cold. When heat is put to air it tends to become lighter and because it is less dense than colder air it is forced upwards by the cool air which continues to press against it. Thus, we define the well-known statement that ‘hot air rises’ for the simple reason that it is being pressurised by the cooler air round about and below it. We note how air moves in a room ‘under pressure’ and it is a fact that winds are caused the same way viz under cooler pressure.

If we were naive and simple (which we most definitely are not) we would kid ourselves that all we need in a loft are inlets along the lower sections of walls to allow the cooler air to pass into the loft and outlets at higher altitudes to permit the cooler air to pressurise the hotter air and force it out of the loft, the hotter air being the carbonic acid gas breathed out by the pigeons in the loft after they had inhaled the cooler, purer air. As I have said, we are far too clever to fail for that idea because your ‘Old Hand’ knows very well that you can’t change the air efficiently in one large compartment (or in one small one) more than three times per hour without setting up unwanted draughts which could be of a harmful nature. The last thing we wish to do is put your birds in jeopardy but you can be quite sure that your old preceptor has far more sense than to commit an elementary error of this kind.

Let us bear In mind that gases, including harmful ones, freely mix together, thereby diffusing impurities as well as purities, so we must get to know more about the art of ventilation before we can hope to provide our bird with a safe and proper home. Perhaps we had better take the example once again of a man sitting in a seated room, breathing the air in it. We know from our tables and statistics that a man can turn out enough carbonic acid gas from his lungs and his skin, each hour, sufficient to render about 3,000 cu.ft. of air unfit for further respiration. A simple calculation will show that this person must be provided with a room l2ft x l0ft x 8ft as an alternative to being the target of nasty draughts. So, we now come to the inescapable basic fact of all schemes of ventilation viz that an animal must be given sufficient room viz ample air space.

If you care to look at ft in another way, you can say that ‘air space’ is really ‘lung space’. We must understand that if there is insufficient room, or air space, the metabolism must suffer from toxic gases which quickly put impurities into the bloodstream. How can any fancier hope to excel when racing pigeons whose blood has been poisoned by carbonic acid gas through loft overcrowding? You can feed your birds on the finest food money can buy and change the drinkers every few minutes, but without benefit to birds who are living in overcrowded accommodation. They would be steadily gassed every day and every night which, though not killing them immediately, would exert a subtle but lethal effect on them. Perhaps now you will realise why I detest ‘small lofts’ and in particular those heartless bureaucrats who are probably the country’s main contributors to the poisoning of racing pigeons.

If I lived in a ‘council house’ and was therefore at the mercy of dictatorial bureaucrats I would not erect a loft at all! Instead, I would construct an aviary with four walls of wire mesh. Then I would drape some transparent polythene sheeting over it. Incidentally, I’m not quite sure about modern council regulations governing the erection of ancillary buildings but I know that up to recent times the council had no Jurisdiction over property that is transparent. In other words, I hold the opinion that anyone could build an aviary with a transparent roof without needing permission from the local authority but please don’t act on this advice without getting good legal opinion, or an opinion from the RPRA, which probably knows the ins-and-outs of modem local by-laws.

I would then insert a wire-mesh floor some 12in above ground level so that birds could not reach the ground below the wire-mesh floor. One could stick a wooden rod or two through both wails of the mesh to provide perches. Nestboxes could be put in the aviary in the proper season and I maintain that birds living in this structure would be healthier and fitter than any birds kept in a loft or structure with wooden or solid walls.

It would be almost impossible for birds living in this way to contract respiratory disease, or anything like it. They would have to be healthy to live, anyway.

The only birds I lost in such conditions were some Belgian squeakers which I suspected of suffering from respiratory disease. I wasn’t sure so decided to take no chance. There were thirteen of them and they went into the aviary one November night. Four of them toppled from their perches so they were indeed affected, but the remaining nine stayed to thrive and prosper. If the four had contracted the disease so had the other nine but the healthy conditions in which they were compelled to live cleared up the trouble once and for all.

As we have seen, a cubic air space of about 3000 cu.ft. is necessary for the well-being of one human but the average quota for animals is 25 cu.ft. for each pound of body weight. As the average racing pigeon weighs only l6oz (1-1 lb) altogether then 9 cu.ft. would appear to be quite sufficient. On the basis of a pigeon requiting about one third of the 25 cu.ft. of air, a small loft 9ft x 9ft x 6ft high would accommodate about 54 pigeons. So much for theory!

However, as pigeon fanciers we know that we are not just beset by the production of carbonic acid gas through pigeon respiration but there are other sources of obnoxious loft gas build up. For instance, what about the pigeons’ droppings? These fall onto the loft floor where they build up all through the night, giving off ammonia.

This brings me back to what I was saying about the diffusion of gases. No matter how much individual gases weigh, they mix freely and instantly, to produce yet another type of gas, some productions being worse than others. In a pigeon loft, where perched birds spend the night building up a floor or perch layer of wet droppings, the said droppings give off ammonia gas which diffuses (mixes freely) with the carbonic acid gas to create an entirely but even more obnoxious gas, known as carbamate gas. This additional hazard militates against the sums we have just been doing in respect to air space per bird. Therefore, a much more liberal amount of air space must be provided if we are to counteract this inevitable drawback.

How is a fancier to know if the production of obnoxious gas to generate atmospheric impurity has reached a dangerous level, affecting the general loft ventilation system? Well, nature fitted him with a very reliable obnoxious gas detector - his nose! If you can smell impurities in the air, then the ventilation is inadequate, in fact, it is downright dangerous. No one should be able to smell ‘pigeons’ in a pigeon loft, nor should any nose be assaulted by the abominable stink of ammonia from droppings. If you can smell either pigeons or droppings, or both, the loft ventilation system should be overhauled at once. To delay the work is to inflict respiratory disease on all the loft’s inmates.

Take your own home for example. If you can sniff unpleasant odours, by way of a general mustiness, two possibilities are imminent: (1) The ventilation system is inadequate; (2) There is ‘rising damp.’ The risk of (2) above is inherent in every pigeon loft which has been erected without adequate damp-proofing, which is to say that a waterproof-course has not been laid between the piers which support a structure on the ground and the loft Itself. Before standing the loft on anything one should first cover the pier or prop with slate, lead impregnated damp course, polythene, or some material which is waterproof and has lasting qualities. Otherwise, rising damp will reach up into the loft and begin to poison the internal air.

Fanciers should know that rising damp’ is not merely moisture moving up the wall of the loft through capillary attraction but it is a living, seething vile bacteria, which destroys as it progresses, with its single task of multiplying its spores (cells) in its course of encroachment on the structure. No good racing pigeons should be exposed to this damnable risk.

The ‘nose detection’ of obnoxious gas can only operate when one is on the point of entering a loft. After some time spent in the loft’s interior the nose stales in its quest for odours and tends to get used to the vitiated air. Therefore, practice sniffing when you enter the loft and if you can smell atmospheric impurities decide to do something about the situation immediately.

As I said, it is necessary for us to do our sums again by taking into consideration not merely the carbonic acid gas exhaled by perched pigeons but also the ammonia gas exuded by the damp droppings. According to the standard adopted by scientists, a loft 9ft x 9tt x 6ft high (486 sq.ft.) would accommodate 24 pigeons. Judged by what I have seen on my past travels most fanciers are keeping double that number of birds in their lofts, thereby Indulging In blatant overcrowding with the worst possible results. Indeed, most of the birds in these lofts will be suffering from respiratory disease which, in most cases, will have escaped the notice of the owner.

When calculating air space in order to arrive at figures which show there is sufficient air to ventilate the structure there is a limit to how high we can go inside the loft. For instance, if we supposed that the loft roof was some 18ft above the floor, the air in the upper layer of some lift would not be deemed air that was available for respiratory purposes to the inmates of that loft. Although the actual accommodating air space height is somewhat of an arbitrary nature (science poses pros and cons) I think we can discount air that stacks up more than 7ft from the floor. This requirement Indicates, in no uncertain manner that floor area is of the greatest factor, not height. This means that loft designers and builders should be encouraged to provide depth (or width) as an important provision towards the ventilation problem.

Air space in buildings which contain chimneys is less critical than buildings which do not contain chimneys, such as pigeon lofts. The chimney does not merely discharge the smoke from fires, it also has the effect of sucking out the used air so that new, fresh air can penetrate the rooms and replace the vitiated air which is being extracted via the flue. I saw ducted ventilation (square wooden ducts installed) in the loft of Van Den Bosche of Ghent. Although the loft was in the attic (loft) of a house which peaked up to a considerable height to the centre ridge, the partners had installed the duct to bring fresh air down from the height to a level some 6ft above floor level. I complimented them on their cleverness and pointed out the remarkable condition of their birds as their response to the purer air they were breathing. It is a fact which so few fanciers will subscribe to, that pigeons in most lofts would react to Improvement made to the ventilation system by assuming a high level of ‘Condition’ of a kind few fanciers have ever seen. I hereby invite my reader to take his nose to his loft and, if he is not entirely satisfied with what he encounters, he sets about the introduction of a system of ventilation which can bestow real benefits on his pigeons.

My own birds occupy loft sections which are 8ft deep, 5ft wide and 6ft 61n high. In a section of this size I allow six pairs of birds to breed, no more. However, it should be borne in mind that apart from the above dimensions I have also installed fittings which I have proved definitely assist the ventilation by helping to keep the fresh air moving through the loft. I will not permit any air inside the loft to ‘dwell’ viz remain static. I require the air to flow into the loft and keep moving until it passes out to give perfect ventilation.

I know there are those who will cry out against this system by pointing out that I have already said that when a loft’s internal air is changed more than three times in an hour draughts are created. Well, what are draughts? A draught is a stream of cold air which is playing into an interior containing warm air. But there is no warm air in my loft! Like those other fanciers who have created ‘east wind pigeons’, I deliberately built my loft to face east and it is wide open to this cold wind. The result is that the air inside my loft is of the same temperature as that of the coldest which is found outside it, therefore no draughts are possible. I wish my reader to understand that you can’t create an ‘east wind’ family of racing pigeons if you pamper your birds and give them heated or ‘protected’ interiors. Why not? Because an ‘east wind’ strain of pigeons can only become so if it develops the kind of plumage which can be guaranteed to keep its body temperature at the correct level (107’F) in the coldest of conditions but no pigeon is going to grow such a thick plumage unless its environment demands growth of that kind. Hence the exposure to east winds.

The secret of keeping the air moving in the loft is to install louvers at floor level and a 4in gap running the length of the rear wall at the position where it meets the roof. In a loft fitted up in this way the air streams from the front and both ends (like the front, the end walls of the loft must also be louvered at floor level) Incidentally the gap in the rear wail must not be louvered but be covered with fine mesh wire.

If this kind of ventilation is installed (and it is the best) the fancier should again use his nose as an air impurity detector, especially when he has nestlings in the nest. Obviously, the hatching out of nestlings means something like a doubling of those sources of supply of carbonic acid gas and the ammoniac gases from the droppings. Can you still smell pigeon and/or ammonia when you enter the loft? If so there is only one thing for it and that is to increase the number of louvers in front and side wails until enough air is streaming through the loft, from front to rear, to keep the air clean and sweet.

In the past, few fanciers were willing to consider the effect of bad ventilation on racing pigeons. They tended to blame a number of other external ponderables for their sad lack of success. Fortunately, more and more fanciers have seen the light and are taking notice of loft design as an influential factor in pigeon racing success. Some things one can ignore in the hope that they will go away but no amount of indifference will relieve a loft of the burdens it imposes on its inmates because of its bad design and lack of real ventilation.

Thursday, October 21, 2010

Principles of ventilation

Principles of ventilation

The basic principle of ventilation in dwellings is to create air circulation from the living space to the service or wet rooms (sweeping principle). Fresh air entrances are placed in bedrooms and living room while air extraction is placed in toilet, bathroom and kitchen. To allow air circulates in the dwelling, transfer grilles can be placed on doors. Air can also circulate below doors when there is enough space between doors and the floor.
A common shortcoming found in Serbian dwellings is the installation of an intermittent small extraction fan in the bathroom without any air supply in the living part. Useless to say that this does not qualify as a ventilation system


Ventilation solutions

Any ventilation solution has two parts: on one hand the fresh air supply and on the other, the evacuation of inside stale air. A ventilation solution must provide enough fresh air but not too much. That would result in waste of heating energy. Based on that common understanding, several systems exist, each of them having pluses and minuses.

Natural supply and extract (Passive Stack Ventilation)

This ventilation system is based on the natural air movement through the dwelling as a result of internal and external temperature differences and wind induced pressure differences. Temperature and pressure differences cause moist air to be drawn up the ducts to be replaced by fresh air through inlet vents situated in the walls or window frames of habitable rooms. A free flow of fresh air from 'dry' to 'wet' areas creates whole house ventilation. 



Continuous mechanical supply and extract. 1. Fresh air distribution system, 2. Grilles for air transfer (air can also pass below doors), 3. Warm stale air extraction, 4. Warm stale air exhaust, 5. Fresh air intake, 6. Filters, 7.8. Ventilator, 9. Sound insulation system, 10. Flow management system (humidity sensitive), 11. Ventilation ducts for air supply and extraction Pre-heating of fresh air (optional),

From uncontrolled air leaks to controlled ventilation

Ventilation used not to be a concern in residential buildings. They were poorly insulated and air leaks on the windows and walls were plentiful. Keeping the place warm was difficult and cost a lot of energy, but air rewenal was naturally done, altought in a completely uncontrolled way. Air leaks are unequally distributed and are not controllable. Their flow vary in time and season and is either insufficient to provide enough fresh air or provide too much.
In a search for better comfort and rationalization of energy spending (after the energy crisis of the 70s), buildings started to be better insulated. Air leaks were greatly reduced and the quest for air tightness was launched. Achieving a low-energy building, requests outstanding thermal insulation, no thermal bridges and excellent air tightness. The natural ventilation of the past, based on construction defects, is not an option anymore.
The only way to maintain a healthy interior and control the spending of energy is to control the ventilation. In modern dwellings, were construction defects are minimal, a controlled ventilation system can provide air renewal that is able to adapt its flow to the inside air humidity and to the occupancy level. In fact, ventilation is such an important system that most European countries have already passed legislation to make ventilation compulsory. Serbia is not at that stage yet.


The fact that passive stack ventilation depends on natural motors, is a big plus: energy saving (no fan), no noise (low air speeds and no fan) and simplicity of maintenance. It is the simplest of all ventilation systems and when it is possible to implement it, it is a very good ventilation solution. Its main drawback also lies in the fact that it relies on natural motors. Passive stack ventilation might be hard to control as temperature, air pressure and humidity level vary greatly outside. It is possible to improve it further by using humidity sensitive air inlets and extract grilles. 



Continuous mechanical supply, natural extract. 1. Fresh air distribution system, 2. Grilles for air transfer (air can also pass below doors), 3. Warm stale air extraction, 4. Natural warm stale air exhaust, 5. Fresh air intake, 6. Filters, 7. Pre-heating of fresh air (optional), 8. Ventilator, 9. Sound insulation system, 10. Electronic management system, 11. Ventilation ducts for air supply and extraction.

 

 

Natural supply / Mechanical extract

This solution is similar to the passive stack ventilation where the exaust of stale air is complemented with a mechanical extract to better regulate its flow. Fresh air is coming from air inlets located in the windows or in the walls of bedrooms and living rooms, while stale air is extracted from wet rooms such as the kitchen and bathrooms. 

The main advantage of this type of ventilation is the fine control it gives on the flow of air extracted from the dwellings. This can be coupled with advanced humidity sensitive regulation systems that can adapt the airflow generated by the fan according to the needs of each wet room. Some systems even include presence detection to regulate the airflow. 
n apartment buildings, this can be implemented through an individual extraction system in each apartment or with a single extraction system for the building.

Mechanical supply / Natural extract

In this solution, the fresh air supply is provided using a ventilator while the air exhaust is natural. This makes possible to filter or pre-heat the air before it is injected in the dwelling. The air intake can also be located anywhere (such as on the roof) which can solve the problem existing with pollution or noise getting through air inlets on the windows, if the building is located in a busy street for instance. 

Because the fresh air supply has to be conducted in all rooms, this solution requires more ventilation ducts and more work. It can be a good compromise mainly if filtering of the air is necessary. 

 Individual or collective treatment of the ventilation in residential building.

 

Mechanical supply and extract

This is the most complex and expensive system in which both flows of air are controlled and regulated using a ventilator. The main advantage of such a system is that it can be implemented with a heat recovery unit. 

The heat recovery unit exchange the heat contained in the hot stale air taken out of the dwelling to warm up the cold fresh air getting in. Depending of the system, as much as 95% of the heat contained in the hot air can be recovered, limiting the loss of energy due to the ventilation system to a minimum


Natural supply, continuous mechanical extract. 1. Natural fresh air intake system, 2. Grilles for air transfer (air can also pass below doors), 3. Warm stale air extraction, 4. Warm stale air exhaust, 5. Ventilator, 6. Sound insulation system, 7. Electronic management system, 8. Ventilation ducts for air supply and extraction.


Conclusion

Ventilation in modern quality dwellings is a necessity for having a comfortable and healthy interior. Yet, in Serbia, it is very often overlooked or implemented badly with a single extract fan in the bathroom and no air intake. Different solutions exist to properly implement a ventilation system and the best one is function of the specifics of any given project. Nevertheless, a good choice has to balance cost, complexity, maintenance and energy spending. When it is possible, the Passive Stack Ventilation offers a simple and economical alternative and that is the one we decided to implement in Amadeo.



Tuesday, October 19, 2010

Ventilation with a Face Mask

Indications
 
Providing positive-pressure ventilation with a face mask and a bag-valve device cna be a lifesaving maneuver. Although seemingly simple, the technique requires an understanding of the airway anatomy, the equipment, and the indications.Face-mask ventilation is used in patients who have respiratory failure but arestill breathing spontaneously and in patients with complete apnea. Face-mask ventilation can be indicated in any situation in which spontaneous breathing is failing or has ceased, including cardiopulmonary arrest.
 
 
 
Contraindications 

 
Face-mask ventilation is rarely contraindicated. However, caution is advised in patients with severe facial trauma and eye injuries. In addition, foreign material (e.g., gastric contents) in the airway may lead to aspiration pneumonitis. In these circumstances, alternative approaches, including endotracheal intubation, may be necessary.
 
Equipment
 
There are many types of face masks, varying in design, size, and construction materials.Transparent masks are preferred because they allow for inspection of lipcolor, condensation, secretions, and vomitus. To maintain a good seal, the mask’s size and shape must conform to the facial anatomy. Thus, several mask shapes and sizes should be readily available.
Various bag-valve designs are available. All have a self-inflating bag and a nonrebreathing, unidirectional valve. The valve is designed to function during both spontaneous and manually controlled ventilation. Because bag-valve devices can operate without an oxygen source, it is important to ascertain that supplemental oxygen is flowing through the bag-valve device when supplemental oxygen is indicated and available. Test the bag-valve device’s capability for delivering positive-pressure ventilation before use. This can be achieved by sealing the bag-valve device connector with your thumb and squeezing the bag with reasonable force. If it is difficult to compress the bag or if air is forced between the connector and your thumb, positive pressure can be delivered.
Whenever possible during face-mask ventilation, suction should be readily available.
You may need to use airway-management adjuncts, such as disposable oral or nasal airways. Before beginning face-mask ventilation, examine the patient’s oral cavity. If possible, remove any dental prostheses or other foreign bodies that might be swallowed
or aspirated

Smowtion

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