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Best Practices for Gas Monitoring
in the Commercial Kitchen

Enhancing Kitchen
Safety through
Strategic Gas Monitoring

Overview

The commercial kitchen is a hazardous area that should be monitored for both toxic

and combustible gas hazards. Whether natural gas or propane is used for

combustion, a variety of cooking equipment (e.g. stoves, grills and fryers) present a

Commercial

kitchens are

one of the most

“

hazardous

commercial

building areas.

constant ammable danger to workers. In addition, carbon monoxide (CO), the by-

product of incomplete combustion, can be present at unsafe levels. Over the last

twenty years, standards for CO monitoring have been developed, with rst-alarm

levels typically set at 25-35 parts per million.

“

Today more rigorous standards for gas monitoring are being developed; those driving

regulatory change vary by state but include many: building inspectors, consulting

engineers, insurance adjustors, re marshals, and life safety experts. More legislation

is inevitable in light of the sobering statistic that 25% of all fatalities in commercial

buildings are due to carbon monoxide poisoning. What’s problematic is, CO is

odorless, so rising CO levels are difcult to detect by humans. According to medical

research, just 0.1% CO in the atmosphere can adversely affect concentration. At 2%

CO levels, breathing reduces to about 50% of the normal rate. Once levels rise to

5-10% people quickly become confused and can lapse into unconsciousness.

The commercial kitchen presents a special case for more rigorous CO monitoring,

as there is a greater risk of CO poisoning from both long-term, low level exposure

as well as short-term, high-level exposure of CO concentration levels.

The First Step: Choose Commercial-Grade CO Detectors

The CO detectors recommended should be commercial-grade detectors. Be advised

that most residential-model CO detectors are not equipped with the same sensing

performance, diagnostics and congurable options as commercial-grade offerings.

A key point to note: a commercial detector will trigger immediately at a pre-

determined set point; however, many residential units alarm only after a time-weighted

duration of over 60 minutes. In addition, the commercial-grade CO detector also will

alarm under any of the following conditions: loss of power, automatic self check of

internal electronic system & sensing element (including a sunset feature). According to

most state codes, a commercial-grade CO detector must detect the gas (and sound

the alarm) at a lower level than a residential-use detector.

Providing kitchen personnel with the highest assurance of effective protection from

carbon monoxide poisoning should be the goal of every kitchen manager. That higher

standard of safety can be realized through one of two system designs: the redundant

gas monitoring system (CO/CO) or a dual gas monitoring system (CO/CH4).

Commercial Cooking
Venting Requirements

Option #1:

Fan Proving System with Internal Manual Reset Valve

Manual

Reset

(Internal)

AC

S

L1

Hood Exhaust Fan

Proving Switch

120/60

L2

Option #2:

Fan Proving System with External Manual Reset

Manual

Reset

(External)

120/60

AC

Hood Exhaust Fan

Proving Switch

S

Manual Reset

Gas Valve

Under the NFPA (54) Code 10.3.5.1 & 10.3.5.2 (2002), ventilating
hoods and exhaust systems shall be permitted to vent gas-red
equipment installed in commercial applications. However, certain

requirements must be met, including:

• These same requirements apply for systems with standing or

electronic pilot ignitions.

• A valve shall be located on the main gas line feeding the
appliances served by the gas hood and shall stop the ow of
gas to the appliances upon loss of draft. No by-pass of the gas
solenoid valve is allowed.

Where automatically operated gas utilization equipment is vented

through a ventilating hood or exhaust system equipped with a
damper or with a power means of exhaust, provisions shall be
made to allow the ow of gas to the main burners only when the

damper is open to a position to properly vent the equipment and

when the power means of exhaust is in operation

• The gas valve must be controlled by a draft proving switch
measuring draft within the hood. The gas valve is allowed to
be open only when the fan is operational or the damper is

100% open.

• The gas valve shall be equipped with a manual reset
(integral or otherwise). The valve must be manually reset only
when the lock-out condition is corrected. The reset cannot

be automatic.

Remote Manual
Reset Gas Valve

Option #3: Most Advanced Design

Redundant Gas Monitoring System with External Manual Reset Valve

Option 3 meets and exceeds the most rigorous

monitoring requirements now being proposed in some

states. To ensure the safety of kitchen personnel and

guests, and to future-proof your monitoring design
against oncoming regulations, option 3 is the way to go.

Under current kitchen management practices, there are at least

three ways to satisfy these requirements:

Option 1: Fan Proving System with

Internal Manual Reset Valve

Option 2: Fan Proving System with

External Manual Reset

Option 3: Most Advanced Design -

Redundant Gas Monitoring System with
External Manual Reset Valve

The shortcomings to options 1 and 2 are:

• No bypass is allowed according to
NFPA code

• Hood switches notoriously fail in this

environment and are easily jumped out
or set incorrectly

• The problem of back draft of damper
system is not addressed

Best Safety Practice: Adopt
Either a Dual-Gas Or Redundant
Gas Monitoring System

The Redundant CO Monitoring System: a Case for Wider

“Two CO

Implementation

monitors

strategically

“

installed ensure
a higher degree

of safety if

one monitor

should fail.”

A system that uses at least two CO (carbon monoxide) detectors as part of a gas

monitoring system design is strongly advised. This dual-sensing or redundant gas

monitoring design meets the requirements of NFPA 54 10.3.5.2.

Under the current code and clarications, a kitchen’s gas valve is allowed to

remain open, even if the hood’s exhaust fan is off, provided that a proper carbon

“

monoxide detector is monitoring the space. However, an intentionally redundant

second CO monitor has been shown to increase the reliability of the system design,

ensuring the probability of continued safety in the event that one monitor fails. In

many hazardous industries, this fail-to-safe design feature is now mandated as a

prerequisite to obtain a work permit; these regulations are the outcome of painful

lessons learned too late. The commercial kitchen, in effect, functions as a small

power plant, consuming up to 60% of the energy load in a commercial building.

In this light, a CO monitoring system should be viewed properly as a life safety

system. A redundant CO monitoring system for the commercial kitchen mitigates

risk to human life by increasing the margin of safety. In conclusion, the oft-repeated

counsel for choosing a CO monitor based on its square foot coverage should not

be the sole means of determining how many detectors are needed in the space!

When installing a redundant CO monitoring system, certain
criteria should be met:

• When the CO monitor fails (or sunsets), according to NFPA code the gas

valve shall be closed and remain so until the device is replaced. No gas

bypass is allowed to feed standing pilots.

• Air sampling from the CO detector should be taken from a minimum of two

separate locations. Again, it should be noted that the square footage of the

kitchen should not be used as a reliable guide to the number of CO monitors

required for adequate coverage. The exact number of CO detectors should

be determined after a site evaluation and in close consultation with gas

monitoring system design engineers.

• The CO detectors shall be interlocked with the gas valve. The gas valve shall

be equipped with a manual reset (integral or otherwise).

• An audible alarm shall sound when pre-determined levels of CO are reached.

Installation Considerations

Locating the Sensor

In a commercial kitchen, special
consideration should be given to the

Installation Height

Detected Gas

CO

COMB

* Note: Most combustible gases are heavier than air, with the exception of methane,

hydrogen, ethylene and acetylene. Sensors for gases that are heavier than air
should be installed approximately 30 cm (1 ft) from the floor. For combustibles that
are lighter than air, sensors should be installed 30 cm (1 ft) from the ceiling, close
to the potential leak source. For guidance on combustible gas monitoring, consult
a gas monitoring system design expert.

Carbon Monoxide 0.968 1-1.5 m (3-5 ft.) from floor

CH

4

Relative

Density

(air = 1)

Varies* Varies*

Installation Height

following installation requirements:

Locating CO Detectors

To determine the best locations for installation of CO

detectors, the main considerations are installation

height and detection objectives. If the primary

application is to obtain the fastest possible leak

detection, the standard practice is to mount the

sensor near the potential leak sources. A drawback

to this approach: the indicated concentration

may not be representative of personnel exposure,

and easy access for the required calibration and

maintenance can be compromised. A common error

The Dual Gas Monitoring System (CO/CH4)

Sequence of operation: A dual-gas monitoring system for the commercial kitchen

uses a combustible gas detection sensor as a remote monitoring source that can

be connected to a primary CO detector, allowing for both combustible and toxic gas
monitoring on a single platform. The primary unit here is mounted a few feet from the
oor, within “the breathing zone” for CO, while the remote unit is positioned above the
cooking equipment to detect CH4, which has lighter-than-air properties.

in the commercial kitchen is installing

the sensor too close to the hood. This

is problematic because heat and grease

build-up in the hood can produce faulty

readings as well as block the sensing

element. To offset this problem, the

recommended practice is to mount

the sensor ten feet from the hood. The

disadvantage to this practice, however,

is that it puts the sensor further from the

source of potential combustion. As the

old adage goes, you can’t have it both

ways; thus, the need for two CO sensors,

or a redundant gas monitoring system.

Installation Height: The two CO

detectors should be mounted in the

kitchen approximately 5 feet from the oor.

This ve foot height corresponds to the

“breathing zone” of most people and is

adopted as the de facto standard. CO is

relatively the same weight as ambient air.

Regulatory Codes and a
Summary of Best Practices

Lawmakers are Turning up the Heat on Commercial Kitchen Safety

In 2012, the NFPA upgraded its Standard 720 for the Installation of

Carbon Monoxide (CO) Detection and Warning Equipment to include the

following clarications:

• 5.8.5.3.5 The location of carbon monoxide detectors shall be based on

an evaluation of potential ambient sources and other criteria (e.g. ows of

carbon monoxide, moisture, temperature, dust, or fumes and of electrical or

mechanical inuences to minimize nuisance alarms).

• 5.8.5.3.6 The selection and placement of [carbon monoxide] detectors shall

take into account both the performance characteristics of the detector and the

areas into which the detectors are to be installed to prevent nuisance alarms or

improper operation after installation. [72:17.7.1.7]

• 9.4.1.2 Each alarm or detector shall be located on the wall, ceiling, or

other location as specied in the manufacturer’s published instructions that

accompany the unit.

• A.1.2 Carbon monoxide alarms and detectors are intended to alarm at carbon

monoxide levels below those that are known to cause a loss of ability to react

to the dangers of carbon monoxide.

Summary: Reducing Risk

Factors that will reduce risk of toxic or ammable gas incidents in the commercial

kitchen include:

• Redundant gas monitoring system

• Good natural ventilation

• Satisfactory fume removal through
ventilation ductwork by natural
draught alone

• Well-maintained ventilation system

• Appropriate ventilation system interlock

• Good user awareness of the risks and

proper documented safety procedures

• Proper use of gas-red appliances

• Regular extraction cleaning of
ductwork, lters and extractors

• Adequate room size for kitchen

• Notices warning that appliances must
not be used without the ventilation

system in operation

For more information on monitoring gases in the
commercial kitchen, contact the experts in gas detection:

Honeywell Analytics. Call [phone].

WP1161_v1 10/14

© 2014 Honeywell International, Inc.

Be sure to use Commercial Grade Gas
Detectors for protecting commercial
kitchen staff and guests