Are there other CO alarm standards or guidelines

Is this CO problem identifiable and is it correctable? Do we need to vacate the premises? Do I have a duty to report this level to an Authority?

Our procedural steps should include rating the levels found and referencing them to reasonable and accepted levels. Many standards for CO exposures come from nationally recognized professional associations or governmental administrative organizations. The medical community has helped establish these levels. All standards are current as of the issue date of this publication.

Many local Authorities of Jurisdiction have living space limits for carbon monoxide. It is recommended you ask the local fire department what their limits are for evacuation, required service or other procedure. In some locations, the regulated gas utility may be the Authority, or the city, county, state inspection department may be.

Bacharach offers common action level standards along with the nationally recognized standards of concentration. Bacharach offers these, as they appear to be of reasonable and common standards of practice. Measurements taken must be referenced in time units as well as exposure concentrations. Often, we are in buildings for small windows of time.

Any increase in PPM from outside to inside warrants further source investigation and is documented, reported and even fixed is common in jurisdictions where a fuel supplier also is considered an Authority of Jurisdiction. This standard is also common to some federally and state funded weatherization programs as well as protocol to some private companies engaged in carbon monoxide testing.

ASHRAE (62-89) (American Society of Heating, Refrigeration and Air Conditioning Engineers)

009 PPM: The maximum allowable concentration for continuous (24 hr) exposure. ASHRAE states the ventilation air shall meet the out door air standard.

009 PPM: This level or lower as an ambient air quality goal averaged over eight (8) hours. This out door air standard is exceeded in many urban areas due to auto exhaust.

009 PPM or more above what you measured outside is the most common action level in the U.S. by local Authorities of Jurisdiction for further testing. Some jurisdictions require fuel shut-off until problem diagnosed and corrected.

10 to 35 PPM is a marginal level in reference to potential or foreseeable problems in some situations. Occupants should be advised of a potential health hazard to infants and small children, elderly people and persons suffering from respiratory or heart problems. If building has attached auto garage, document CO levels in garage. Accept this level as normal where unvented appliances are in use. These levels are unacceptable when originated from vented appliances.

035 PPM: This level or lower as an ambient air quality goal averaged over one (1) hour.

035 PPM is also a common action level for fire department or other emergency responders to utilize self contained breathing apparatus when occupation of that environment is to be sustained by that responder.

035 PPM or less averaged over an 8 hour day within that workday is a common goal of specific States Occupational Health and Safety Administration or similar state entity. This is also a common goal of many employers despite higher regulated concentration standards and may require the measurement of several simultaneous reference locations.

050 PPM: Maximum allowable concentration for a workers continuous exposure in any eight (8) hour period. This 8-hour average requires continuous measurement and accurate reporting in the workplace.

36 to 99 PPM is excessive. Medical alert. Conditions must be mitigated. Ventilation required. Always test garage space. Individually test combustion appliances. All repair is to be conducted by a qualified technician with proper test equipment.

100 to 200 PPM is dangerous (and is a common building evacuation standard.) Medical alert conditions. Suggested occupant health inquiry. Advise that someone else drive them to seek medical help; 15 minute maximum exposure upon discovery. Report incident to Authority of Jurisdiction.

200+ PPM is extremely dangerous. Universally accepted as an evacuation action level.

The health of occupants should be monitored, emergency conditions exist. Building should be ventilated and searched for additional occupants. Combustion systems should be thoroughly tested for CO production and dispersion. Report incident to an Authority of Jurisdiction.

Carbon monoxide measurements in flue gases also must meet specific concentration standards. Though CO concentration standards have existed for appliances and other combustion systems for many years, lack of testing and misunderstanding of CO measurement has occurred.

As stated earlier, carbon monoxide can be measured in flue gases as CO PPM or CO PPM Air-free. Appliance manufacturers must produce units that comply with measurements of CO Air-free that are less than the listed maximums.

The following CO PPM Air-free measurements are offered along with common CO PPM standards found in jurisdictions where single sensor CO instruments are used.

Bacharach offers instruments that calculate CO PPM Air-free for you or you can use the following math. Remember that an oxygen (O2) measurement must be taken in the flue gas along with CO PPM to calculate CO PPM Air-free. See the chart on page 32 for a CO Air -free reference where the math has been completed.

200 PPM CO Air-free is the maximum concentration from an unvented space heater.

To many technicians who have been and are performing combustion gas tests regularly, these concentrations are extremely high in reference to CO levels that can be expected from combustion systems finely tuned and maintained.

Additionally, CO Air-free measurement is not always performed due to lack of understanding about the requirement and lack of technicians’ understanding about the importance of O2 measurement in establishing the efficiency and safety parameters of combustion systems.

This manual has discussed air measurement standards for CO in ambient air and flue gas standards for CO Air free. Monitoring flue gas readings commonly occurs across North America. The most criticism about flue gas testing often times comes from technicians or companies that do not test. One of the most common argumental phrases offered against testing goes something like this: “All furnaces produce CO. If there is a vent on the furnace, you don’t have to worry about it.”

Fortunately, many technicians and companies began and continue to test flue gases on furnaces, water heaters, ovens, boilers and other systems. It is easy to come to agreement with technicians who do test combustion gases routinely: Carbon monoxide problems can be identified and minimized.

It is common to find technicians, gas utility company personnel and others who do not understand the CO Air Free measurement and who often mix Air Free and non-Air Free measurement numbers.

Many technicians and inspectors utilize CO test instruments in the single sensor form (like the Bacharach Monoxor II). The action levels they use for how much CO is too much in flue gases is reported in CO PPM not CO PPM air free because the excess air in that flue gas sample has not been calculated out of the reading.

Therefore, the CO in PPM should be a significantly lower number than the CO Air Free measurement ceiling offered by ANSI, EPA, AGA or other governing bodies signifying those levels within that measurement parameter. (We will learn about flue gas content in the Combustion Analysis section of our training. However, knowing that an efficiently performing natural gas system’s flue gases, as an example, generally contains 7 to 9% O2.

Utilizing our CO Air Free formula, we would calculate the furnace ceiling amount of 400 PPM CO Air Free to be equivalent to around 225 PPM CO and higher when using single gas instrument.

The following concentrations reference measurement commonly found standards for gas systems across North America where single sensor instruments (like the Monoxor II) are being used to measure CO in combustion gases. Gas utility, Energy Programs, Home Inspection Companies, HVAC Companies and others commonly reference these concentrations. It is felt that these concentrations are readily achievable and within reasonable expectations of service work.

It is vitally important to discover and work within the local Authority of Jurisdictions standards for CO concentration limits in flue gas. All concentrations are referenced to a steady-state or stabilized condition of the systems operation with combustion gas sampling points before the draft hood of an appliance or other entries of dilution air. Test procedures and conditions are examined in the following sections of this manual.

Less than 100 PPM Gas furnaces, space and water heaters usually considered safe and left in operation. Annual tests. It is reported to be as low as 25 PPM in some weatherization programs. The more testing performed, the more the technician understands what is achievable and reasonable.

Less than 150 PPM Common ceiling concentration for unvented gas oven emission. Repair recommended if over this amount.

100 -200 PPM Gas furnaces, space, water heaters and boilers require further testing and correction. Not necessarily immediately lethal concentrations of CO but conditions generally found to be correctable within parameters of normal service work. Systems are generally left in operation with set time limits for correction to have been enacted.

200+ PPM Often times gas systems are shut off and/or corrected when concentrations exceed this concentration.

225+ PPM Can be expected to exceed Air Free Standards of 400 PPM in furnace flue gas if Oxygen found to be within 7 to 9 %.

Tests should be taken during actual operating conditions. If more than one appliance is in operation, along with common mechanical exhaust equipment (clothes dryer, bath exhaust, etc.), the tests may reveal different measurements than when the appliances are tested individually or alone.

The top horizontal column is CO in PPM as measured with single CO sensor instrument. The left vertical column is measured O2 %. Move to right and under measured CO for CO Air Free calculation.

CO Air Free is a unit of measurement designed to compensate for excess air in flue gas. No single CO sensor instrument has the capability to take the measurements necessary for this calculation; Oxygen and carbon monoxide must be measured. (See page 29 for CO Air Free flue gas standards.)

(NOTE: If an 11 % O2 were in flue gas, the CO Air Free measurement would be over 400 PPM CO Air Free and exceed ANSI Standards. If you don’t measure CO AND O2, you don’t know.)

Carbon monoxide has a natural tendency to rise in temperatures normally found inside buildings. At freezing temperatures, carbon monoxide is heavier than air. Please keep in mind that cold days in areas of high automotive activity, out door ambient CO levels may be more noticeable than on days above freezing.

Other combustion by-products can contribute to poor health symptoms even when CO is not produced. These by-products include NOX gases and excessive CO2. Acidic moisture from combustion gases can also be harmful.

Though carbon monoxide is odorless, a distinct pungent odor can occur (but not always) during incomplete combustion. Aldehydes are a by-product of incomplete combustion and come with this pungent odor. Often times this odor is mistaken by the consumer as a gas leak. Auto exhaust may also have an odor of raw fuel.

The sneaky part about carbon monoxide is most of the time it does not have an odor.

Carbon monoxide is given off by the incomplete burning of solid, liquid or gaseous fuel. This occurs when there is not enough oxygen mixed with the fuel and/or proper combustion conditions are not met. Variation in combustion conditions can result in varying levels of CO.

What is the fuel being used? How many BTU’s per cubic foot is there or how many BTU’s per gallon? We have to know the fuel.

1. Flow of fuel is specific – measure it. Measure in water column inches or PSI (Pounds per square inch). Always check manufacturer specifications.

2. Air and fuel mixtures – measurable. Combustion analyzers offer O2, CO, flue-stack temperature measurements. CO2, efficiency and CO air free are calculations. Combustion air is adequate, to code and does not interfere with combustion systems performance.

3. Fuel burns completely, without impingement or interference. Limited CO production.

4. Systems with vents shall draft without interruption and installed as specified in accordance to vent manufacturers sizing, installation and performance requirements.

Carbon fuels require air and ignition temperature for combustion to occur. In this course, combustion will be referred to as controlled combustion or explosive combustion. In both types, all properties are required; take one away and combustion will cease.

Controlled gaseous fuel, mixing with air containing sufficient oxygen, ignites when specific heat is supplied to the mixture. Fuel and oxygen burn as long as their individual concentrations maintain a balance respective to their properties of combustion.

A flooding of fuel with O2 may prevent ignition even though enough heat is present. Too much O2 with the fuel will keep the carbon molecules from interacting and prevent ignition, even though sufficient heat is present.

Explosive combustion is very rapid burning which is not under control. Not all natural gas-air- mixtures will burn. Mixtures with zero to four per cent natural gas in air are too lean to burn or explode. Mixtures of 4% to 14% natural gas can burn with a controlled flame and can also explode. Whether or not an explosion will occur depends mostly on whether a gas-air mixture is allowed to collect before it is ignited. 4 and 14% are referred to as the lower explosive limit (LEL) and the upper explosive limit (UEL).

This chart shows the flammability limits for natural gas. Ignition occurs between lower and upper explosive limits. Ignition temperature for natural gas is 1100°F to 1200°F. Flame temperature of natural gas is around 3000°F.

LPG or propane flammability limits are 2.4%(LEL) to 9.5%(UEL). Ignition temperature for propane is 920°F to 1020°F. Maximum flame temperature of propane is 3600°F.