Toxicity of Carbon Monoxide Gas Exposure, Carbon Monoxide CO Poisoning Symptoms, Carbon Monoxide Exposure Limits, and Links to Toxic Gas Testing Procedures
IF YOU SUSPECT CARBON MONOXIDE POISONING GO INTO FRESH AIR IMMEDIATELY and get others out of the building, then call your fire department or emergency services for help.
CO POISONING SYMPTOMS - Carbon Monoxide Poisoning Symptoms
Carbon monoxide characteristics
Carbon monoxide (CO) is a colorless, odorless, tasteless gas that, physiologically, is a chemical asphyxiate. When inhaled, it combines with hemoglobin more readily than does oxygen, displacing oxygen from hemoglobin and thereby interfering with oxygen transport by the blood. In other words, breathing carbon monoxide can lead to asphyxiation - unconsciousness and even death.
A person suffering from carbon monoxide (CO) intoxication may have these symptoms:
1. first experience euphoria (similar to the effect of a martini or two)
2. then headache
3. and possibly vomiting as the concentration of carboxyhemoglobin in the blood increases.
Other symptoms of Carbon Monoxide
• Weakness
• dizziness
• Lethargy
• Confusion
In addition to neurological effects, heart damage has also often been reported in CO or carbon monoxide poisoning cases - see comments below.
Safety Suggestions: Install Carbon Monoxide Detectors in addition to Smoke Detectors
Carbon monoxide detectors are inexpensive and readily available, both as a battery-operated unit and as a unit that plugs into an electrical outlet in the home. No home should be without this safety protection, and homes with gas-fired equipment (natural gas or LP propane), space heaters, or other sources of risk should be extra cautious. Smoke detectors do not protect against carbon monoxide poisoning, and the opposite is also true. Carbon monoxide detectors do not warn of smoke or fire.
Inspecting Buildings for Visible Evidence of Conditions Likely to Produce Dangerous Carbon Monoxide Gas
The fact that you cannot see nor smell dangerous carbon monoxide gas does not mean that there is nothing to look for when assessing the safety of heating equipment. Not only are there easily spotted installation errors (the first list below), there may be more subtle but easily visible errors if you know what to look for (the second list below).
Visible building conditions risking carbon monoxide hazards
This is by no means the complete list of errors that can cause dangerous carbon monoxide exposure in buildings, but here are some common foul ups outside of the workplace that can cause dangerous levels of indoor carbon monoxide:
• Space heaters: improper use of gas or kerosene fired heaters can produce high indoor CO levels. Warning: Never go to sleep in an enclosed space with a space heater left operating. In addition to the CO hazards there is a risk of oxygen depletion which can also lead to asphyxiation.
• Gas fired central heating equipment combined with:
o Improper venting, blocked, under-sized, over-sized, missing parts, improperly sloped chimney or flue. A variety of errors can cause a failure to vent combustion gases out of the building, allowing dangerous flue gases to build up indoors.
o Inadequate combustion air. If a heating appliance is installed in a small confined space it must be provided with outside combustion air. A service technician may tune and inspect a gas-fired boiler with the boiler room door open, finding that it seems to operate fine. When s/he closes it on leaving, there may be an inadequate or no opening for combustion air into the room.
o Venting small appliances into large cold chimneys: Installation of small, higher efficiency gas-fired equipment into old homes at which the appliance is vented into a large (cold) masonry chimney. In such instances the heater may never develop sufficient heat and draft to actually vent up the chimney.
o Also sometimes water heaters are left venting into a too-large, too-cold masonry chimney after a gas-fired boiler is converted to a high-efficiency direct-vent (no chimney) unit. One of my clients developed headaches every October - an event I traced to this condition in Poughkeepsie, NY. [DF re E.B. case 1988].
• Car exhaust, such as to occupants of rooms adjoining or even above a garage where car engines are left running
• Un-vented gas fired water heaters often found venting directly into a basement utility room or even directly into a living area or bedroom.
Other clues which can suggest a risk of carbon monoxide hazards in buildings
• CO detector alarms Do not ignore this first line of defense. Install CO detectors near the heating equipment as well as in sleeping areas of the home. People have died after not believing their CO detector and taking out the batter to silence the annoying device which they believed was malfunctioning.
• Missing parts: Gas fired water heaters, furnaces, boilers which are missing flue vent connector components such as draft hoods and flue gas spill detection switches - it can be difficult to spot that something is missing unless you know what's supposed to be there. Review this topic with a trained heating service technician or plumber.
• Clogged heater draft hood from hair or other debris
• Signs of flue gas spillage Blocked flues will result in combustion gas spillage back into the building. Often this will cause:
o Rust on heating equipment at the point of flue gas spillage - you can detect this even when the equipment is not operating
o Rusty debris on the top of gas fired heating equipment below the draft hood
o Water condensation on building surfaces may occur if gas-vented appliances are venting back into the building, especially on cool basement surfaces - you can only observe this when the equipment is operating
o Odors of combustion products: while CO and CO2 are themselves odorless, if they are spilling from heating equipment, odors of other combustion products may be notices.
Testing for Carbon Monoxide
In addition to the installation of CO monitoring alarms in buildings, a variety of electronic and gas sampling equipment is available to make spot checks for hazardous gases.
While a "positive" indication of a gas is an important indicator of a hazard, a "negative" or "not found" result is nothing to rely on.
The fact that dangerous levels of CO are not present in a building at a particular instant is absolutely no guarantee that dangerous levels of CO (for example) may not occur even moments later. For example, opening a window, turning on a fan or clothes dryer, closing a door and similar innocent acts can significantly change air flow, combustion air, and other building conditions.
Therefore spot tests for dangerous gases should not be relied upon to guarantee building safety. This is why the list of visual inspection items and proper heating equipment maintenance are so important.
MEDICAL EFFECTS of CO - Medical effects of Carbon Monoxide (CO) Poisoning
Many sources I (DF) reviewed indicated that if carbon monoxide exposure was sub acute, that is if the person did not lose consciousness and was removed from the CO exposure before losing consciousness, then any medical effects were temporary. Indeed detection of CO exposure at a hospital is problematic since CO leaves the bloodstream quickly once a person is exposed to normal air. However there is evidence that lasting physical damage may occur from carbon monoxide exposure, though the popular press has not (2006) discussed the exposure level and duration necessary for these effects.
Heart muscle damage occurs from Carbon Monoxide (CO) exposure, screening recommended
31 January 2006 - The New York Times Science Section reports on a new study, released in JAMA's January 25 2006 Magazine Issue, and which indicated that people exposed to carbon monoxide suffer damage to their heart muscles and are at much greater risk for heart attacks in later years. The Times article asserted that CO Poisoning results in 40,000 emergency visits a year in the United States - the most common accidental poisoning event in the U.S. with an annual average accidental death rate of about 1000 people and average suicidal death rate of about 2400 people. [U.S. CDC] Five percent of such patients die in the hospital. Research was not cited regarding sub acute exposures and exposures which do not result in a visit to a hospital. -- New York Times Science Section, January 31, 2006 p. F6, "After Crisis, Carbon Monoxide Still Takes a Toll."
The carbon monoxide exposure and heart muscle damage study was led by Christopher R. Henry, Minneapolis Heart Institute Foundation, in the current [Jan 2006] Journal of the American Medical Association The study examined the medical history of 230 people exposed to carbon monoxide and treated at hospital between 1994 and 2002, following their health to 2005. After 7 1/2 years, in this otherwise low risk (of heart failure) population, 25% of the originally-surviving patients had died - a rate about three times the average heart failure death rate statistic. For people who had suffered heart muscle damage the mortality rate was 38% with half of the mortalities being (apparently) traced to cardiovascular problems. The study concludes that people who are exposed to carbon monoxide should be screened for heart muscle damage. Heart muscle damage from CO poisoning (in the study) was characterized by elevated levels of cardiac troponin I (a type of protein) or creatine kinase-MB (a type of enzyme), and/or changes in diagnostic electrocardiogram (ECG). -- DJ Friedman paraphrasing the NY Times article and JAMA's news release regarding this study.
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Light Commercials
Ductwork Installation
When I was writing my “Ductwork Installation Guide” I've considered that the next guide is going to be to light commercial ductwork installation. But I wasn’t sure that there is a market for this kind of a manual.
However, nowadays a slump in the house market is driving HVAC companies from residential to light commercial installation. If you are working in this kind of company you may face a different environment and meet unexpected difficulties.
In general, light commercial installation is easer than the residential one, but it requires a different approach and an installer constantly finding different types of equipment and ductwork to install. Someone can do the work for 10 years and still find something new . Also different kinds of commercial buildings will make an installer run even a familiar system of ductwork differently. So, I've decided to create this page on my website.
The purpose of this page is:
- To help newcomers with all my knowledge to accommodate a new profession.
- To find out for myself if anyone actually needs this kind of help.
So, if you have any questions you can contact me on this page.
Here you can see some of the pictures which I took a long time ago for the “Light Commercial Ductwork Installation Guide”:
  
Supply duct Supply duct above the sprinkle line Y-branch
  
Connection of the supply duct to the plenum Smoke detector Floor penetration
  
8” heat run 8” heat runs Duct hanging
  
Bath fans exhaust pipe Diffuser connection Linear Register
Question:
“me and a guy are hanging commercial duct we both have 10+ years experiance between us when we come off the sicissor lift to look down at the duct work it looks twisted, we are very experienced at hammering duct work together, i dont get why it is twisted, the duct goes together easy with drives”
So, here are several rules you have to follow when running the duct:
1. Hangers:
- It’s always better to put all hangers on for the same duct size.
For example, if you have to install a 40’ of 30” x 14” duct and the distance between the trusses is 6’ you have to hammer on 6 pairs of hangers.
- When you are measuring where the hangers should be cut, use an electrical conduit. They are always 10’ long and it’s very easy to put on an additional piece to length.
2. Ductwork:
- When you snap a piece of duct together it would be better if sides are matching, but it’s not a big deal if not.
- Don’t put any screws in the seams.
3. Hanging the ductwork:
- Every next piece of duct must be hung with the seam on a different side.
- Don’t screw a hanger to the bottom of the duct if there is a seam.
- Don’t try to fix twisted ductwork until first transition or 90* is installed or all the system will be done.
- If the system of the ductwork is twisted push the corners which are down and up from both sides.
- Secure you job with the screws at the bottom of the ducts.
Space Cooling Load Calculations
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Adjustable curb Tall cone Curb
  
Zoning, bypass damper Round ductwork Zoning damper
Question: I would like to know how the hangers are attached to metal beams. Also were the fire dampers should be in commercial applications.
Thank you.
Answer: Hangers or straps usually are attached by “Caddy strap hangers”. There are several types of them, but   the most usable are shown on fig.1 (twisted) and fig. 2 (straight).
In order to attach the hanger strap to the “Caddy strap hanger” you have to fold approximately 1” – 1 ½” of it by using simmers, long nose pliers or hands, hook up the caddy strap and smash the hanger strap with the hammer. After that you just have to hammer it to the metal beam.
Because there are many types of metal beams: some of them are thinner and some of them are thicker, the “Caddy strap hangers” are made to fit thicker or thinner applications.
Fire Dampers
Fire Dampers are typically intended to be used as part of the HVAC duct system when passing through a fire rated barrier (walls, partitions, floors). The trigger mechanism is a heat fusible link that when activated, impedes the migration of high temperatures into and through the duct system.
UL, AMCA and Damper Manufacturers Require "once every 6 months" Damper/Actuator cycling to ensure proper operation of fire/smoke and smoke rated Dampers during a Fire event.
Fusible links
Fusible links are temperature sensitive fire protection devices designed to be part of a fire protection system. The system is activated when the ambient temperature increases to the point that causes the fusible link to "break-apart". At the point of breakage, it releases the pre-loaded fire protection device, thus restricting the spread of fire.
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Tags
how to install rectangle register boxes on sprial ductwork, commercial hvac ductwork photos, installing ducts for air exchanger,
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