Flashcards in OPNAVINST 5100.19E CH B2 Deck (22)
To obtain accurate and reliable data on heat stress conditions, ships shall conduct heat stress surveys to record
dry-bulb (DB), wet-bulb (WB), and globe temperature (GT) readings.
The Navy uses either a wet-bulb-globe temperature (WBGT) meter or an automated heat stress system (AHSS) to measure each of the above temperatures.
The WBGT index and physical exertion level are used determine how long an individual may be exposed safely to
heat stress conditions.
factors that reduce physical stamina and enhance susceptibility to heat stress illness are dehydration,
lack of sleep, illness, use of medication, drugs, alcohol, and
the presence of atmospheric contaminants such as combustion
gases or fuel vapors.
Heat acclimatization occurs gradually, usually requiring three weeks
or more (although most of the process occurs in the first week).
HEAT STRESS ELEMENTS:
a. Monitoring and surveying of heat stress conditions.
(See paragraph B0204.)
b. Establishing safe work schedules in heat stress
environments. (See paragraph B0205.)
c. Investigating and reporting personnel heat injuries.
(See paragraph B0204f and reference B2-1.)
d. Training. (See paragraph B0206.)
e. Recordkeeping. (See paragraph B0204c(3)(f).)
The commanding officer shall:
) For ships without an automated heat stress system (AHSS) installed, ensure at least two portable, calibrated, and
operable WBGT meters are available onboard.
(7) If an AHSS is installed, maintain at least one portable, calibrated, and operable WBGT meter on-board in the event that the automated system should fail.
For submarines, the MDR conducts heat stress surveys in engineering spaces.
Evaluation and designation of potential heat stress areas is part of the industrial hygiene survey.
“No Calibration Required” (NCR) stickers are not required to be placed on DB thermometers.
Placement of the DB thermometers may be in or out of the ventilation air stream but must be hung at least two feet from any supply ventilation terminal/opening.
Thermometers shall be
hung with a non-heat conducting material such as plastic tie-
wrap or string (never hang with metal wire) and positioned to
minimize the influence of any adjacent or local heat or cold
sources (avoid direct contact between thermometer and hot/cold
thermometers do not require calibration, so if found inaccurate,
the hanging DB must be relocated, replaced, or validated by
aligning the etch mark with the freezing point (32 degrees
A DB thermometer shall be temporarily mounted to
monitor conditions where repairs or maintenance are being
performed in a heat stress area.
Automated Heat Stress System. The AHSS units shall be mounted in a position so they indicate the most accurate representative temperature for the area where workers/watchstanders spend the majority of their time.
Dry-bulb thermometers must still be mounted on ships with
The ship shall record DB temperature readings when the ship is underway or when potential heat stress conditions exist while in port.
Assigned personnel shall monitor compartments as follows:
(a) Every four hours for manned spaces if DB
temperatures do not exceed 85 degrees Fahrenheit.
(b) Every hour for manned spaces if DB
temperatures exceed 85 degrees Fahrenheit.
(c) Every hour at temporary installations where
the DB temperature exceeds 85 degrees Fahrenheit during repair
or maintenance operations.
When surveying a work or watch station using the WBGT meter, the surveyor shall position the meter where the worker/watchstander would normally stand or where the intended
work is to be performed, with ventilation arranged to provide
normal ventilation at that location.
The operating range for the RSS-220 and Vista Model 960
WBGT meters is 65 degrees Fahrenheit to 150 degrees
Fahrenheit. The operating range for the AHSS is 32
degrees Fahrenheit to 150 degrees Fahrenheit and 10% to
95% relative humidity. Use of these meters outside of
this range will not provide accurate temperature
The heat stress surveyor shall conduct the first WBGT measurement in the workspace after the meter has been in the space five minutes to enable it to equilibrate to the surrounding area. As the meter is moved from one site to another, the meter should be at each site for three minutes to allow for stabilization of the first reading (DB) in the series to be taken.
Ships using a database or the AHSS may use a
computer printout for the heat stress survey sheet.
At all manned watch/workstations within the
space whenever the temperature from a permanently mounted
hanging DB thermometer reaches or exceeds the following
PHEL I through III
Watch/Work length 4 hours or less DB => 100°F
Watch/Work length greater than 4 hours DB => 90°F
PHEL IV through VI DB = 85°F.
Under normal operations, routine watches in engineering spaces are expected to be four hours at a PHEL III or lower. PHEL IV through VI apply to above average work rates.
Recovery Time for Personnel Reaching Exposure Limits:
Supervisors shall direct personnel standing watch or working in spaces in reduced stay times (except in
operational emergencies as directed by the CO) to leave the heat stress environment prior to the expiration of the PHEL stay time. These personnel shall move to a cool, dry area conducive to
rapid physiological recovery (an area with a DB temperature of
80 degrees Fahrenheit or less).
Supervisors shall direct personnel experiencing
heat stress symptoms while standing watch or working in the
workspace, to report immediately to the MDR for evaluation.
Drink more water than satisfies thirst, but not
more than 1.5 liters (about one and half quarts) per hour. Do
not wait until you are thirsty to start drinking (scuttlebutts
must be readily available and in working order).
A device that has
proved very effective in helping personnel to stay hydrated on
flight decks, steam catapult spaces, engineering spaces, laundry
and in other hot locations on ship is the Camelbak® (or
equivalent) drinking system. It holds 1.8 liters of water and
is worn like a backpack with a straw mechanism that allows the
person to drink anytime or anywhere. The Camelbak® (or
equivalent) has proved very effective in helping to keep
personnel hydrated especially in areas such as the Arabian Gulf.
where fire retardant or fire-fighting
clothing is required, wear clean clothing composed of at least
35 percent cotton (more natural fiber content allows more
effective evaporation of water from clothing).
The use of using cooling vests that contain paraffin-based
phase change material is not recommended.
is flammable and may release toxic vapors when burning.
NAVENVIRHLTHCEN shall provide a fiscal year-end
summary of shipboard heat stress cases from the WESS database by
type of operation, and ship class to CNO (N09F).
The PHEL curves were
developed and are accurate for normal, healthy, heat-
acclimatized personnel who have had adequate rest, (six hours
continuous sleep in the last 24 hours), adequate water intake,
and adequate recovery time from previous heat stress exposure
(two hours recover for every 1 hour exposure or four hours
Personnel are assumed to be wearing clothing consisting of a least 35% cotton fiber, not containing starch,
and readily permeable to water transfer.
Heat stress is any combination of air temperature, thermal radiation, humidity, airflow, workload, and health
conditions that may stress the body as it attempts to regulate
Recognizing personnel heat
stress symptoms and obtaining prompt medical attention for affected persons is an all hands responsibility.
If someone entering a
workspace or area for the first time in approximately four hours
or more can smell the odor of stack gas and/or fuel vapors, then
a harmful concentration may be present.
Impact of Fuel Combustion Gases (Stack Gas) and Fuel Vapors on Exposure Limits.
Personnel should be checked for the following symptoms:
1. Eyes watering and/or burning.
2. Difficulty breathing.
3. Tingling or numbness of the tip of the tongue, tip of the nose, finger tips and/or toes.
All hands shall receive heat stress training upon
This training may be conducted by showing the
heat stress videotape "Play it Cool: Heat Stress Prevention
Afloat" (8055801-DN). At a minimum this training must include:
(1) Heat stress health hazards;
(2) Symptoms of excessive heat stress exposure;
(3) Heat stress first aid procedures;
(4) Heat stress monitoring; and
(5) Causes of heat stress conditions.