NFPA 22: Standard for Water Tanks for Private Fire Protection

The purpose of this standard is to provide a basis for the design, construction, operation and
maintenance of water tanks for private fire protection.
NORMALIZED SIZE
The standardized sizes of net capacity for steel tanks must be the following:
Table
Capacity of Standardized Tanks
a) 5000 gallons (18.93 m)3)
b) 10,000 gallons (37.85 liters)3)
c) 15,000 gallons (56.78 m)3)
d) 20,000 gallons (75.70 m3)
e) 25,000 gallons (94.63 m)3)
f) 30,000 gallons (113.55 meters)3)
g) 40,000 gallons (151.40 meters)3)
h) 50,000 gallons (189.25 m)3)
i) 60,000 gallons (227.10.93 m3)
j) 75,000 gallons (283.88 m)3)
k) 100,000 gallons (378.50 m)3)
l) 150,000 gallons (567.75 m)3)
m) 200,000 gallons (757.00 m)3)
n) 300,000 gallons (1135.50 m)3)
o) 500,000 gal (1892.50 m)3)
Source: NFPA22.2018
Construction Materials
The plates to be used must be made of one of the following materials.
ASTM A36: Carbon steel alloy, high strength structural steel, low
High Strength Steel Plate Alloy
ASTM A572: High strength low alloy steel used in a variety of
structural uses
ASTM A283/A283M, grades A, B, C, and D: Carbon structural steel used
for applications requiring low to medium tensile strength. This grade is
used in the manufacture of storage tanks and low-pressure containers and
controlled temperature.
When using plates with thicknesses greater than ¾ inch (19.1mm), the ASTM material
A283, grade D, cannot be used. In this case, materials such as ASTM A131, grades A,
By C; or ASTM A572, grades 50 and 60, will be used as alternatives. (NFPA 22, 2013, P.22-
10)
Tank Location: The location of the tanks must be such that the tank and the
structures are protected against exposure to fire. (NFPA 22, 2018, p. 22-10)
Water Level Indicators
The identification plate should also serve as a water level indicator by a
raised arrow that is easily observed. The tank plate must be marked with the
registration "line of 2/3 of capacity" in raised letters or stamped behind the glass of the
indicator and must be positioned so that the arrow is at the water level when
The tank is two-thirds full. Regarding the horizontal tanks, the capacity line of
two thirds. (NFPA 22, 2018, p. 22-17)
Steel pipes
Steel pipes must comply with ASTM A53/A53M, Type E, Type F, Type S, Grade Ao
Grade B, steel pipes less than 2 inches (50 mm) should not be used.
All steel pipes of 6 inches (150 mm) and larger must be Schedule 40. (NFPA
22,2018.p. 22-37.
Tank discharge
The discharge pipe must be sized to supply the required amount of water.
for the fire protection system, it must not be smaller than 4 inches.
(102 mm) in no case. The discharge pipe must be connected to the bottom of the tank by
through an accessory that extends 2 inches (51 mm) above the bottom of the tank for
to form a settling basin and prevent sediment from entering the system.
There must be a listed tension valve or horizontal cotter pin and an indicator valve.
listed in the discharge pipe, indirect below or near the tank. (NFPA 22, 2018, p. 22-16)
Control Valves
A control valve must be installed as indicated on the discharge pipe of each side of the
check valve, and the valve on the discharge side should be placed between the valve of
retention and any connection from the tank discharge to other pipes. (NFPA 22, 2018 p.
22-38).
Filling pipe
It consists of a fixed pipe connected to the water supply for filling the tank. The
means to fill the tank must be able to ensure a full tank in a
no more than 8 hours. The tank must remain full and its level must never be lower
4 inches (102 mm) below the nominal water level. (NFPA 22, 2013, P.22-39)
NFPA 14 Standard for the Installation of Standpipe and Hose Systems
This standard contains the minimum requirements for the installation of vertical piping systems.
hose.
Connection
Firefighters connection. - For automatic vertical piping systems, a connection through
from which firefighters can pump supplemental water into the sprinkler system, piping
vertical or another accessory water system for fire extinguishing in supplies
existing water supplements.
Firefighters Connection. - For manual vertical pipe systems, a connection through
which firefighters can pump the primary water supply to a manual system of
vertical piping to the demand required by the system.
Hose Connection. - A combination of equipment provided for the connection of a hose.
to a vertical piping system that includes a hose valve with a threaded outlet.
(NFPA 14, 2017, p. 14-8)
System Demand
The required flow rate and residual pressure from a water supply, measured at the point of
connection of a water supply to a vertical piping system, to deliver the flow rate
of total water and the minimum residual pressures required for a vertical piping system
in the hydraulically most remote hose and the minimum water flow rate for connections
of sprinklers or combined systems. (NFPA 14, 2017, p. 14-9)
Type of System
Class I System.-A system that provides 65mm (2 ½") hose connections for supply
water for use by firefighters and those trained in handling heavy jets for
fire.
Class II System.- A system that provides 38 mm (1 ½”) hose stations to supply
water for use primarily by trained personnel or by firefighters during the response
initial.
Class III System.- A system that provides 38 mm (1 ½”) hose stations to supply
water for personal use trained and hose connections of 65 mm (2 1/2 '') for
supply a large volume of water for use by firefighters and those trained in it
heavy stream management for fire. (NFPA 14, 2017, p 14-9)
Valve
Pressure Reducing Valve. - A valve designed with the purpose of reducing pressure.
water flowing downstream, under flow conditions (residual) and no flow conditions (static). (NFPA 14,
2017. p 14-9)
Hose Stations.
Closets and Cabinets
The cabinets and lockers used to contain fire hoses must be of a size
that allows the installation of the necessary equipment at hose stations and designed so that
do not interfere with the prompt use of the hose connection, the hose and other equipment in the
moment of the fire.
Inside the cabinet, the hose connections must be located in such a way that there is enough
less than 1 inch (25.4 mm) between any part of the cabinet and the valve handle when it is
can be found in any position range from fully open to fully closed. The
the cabinet must be clearly identified. (NFPA 14, 2017, p 14-14)
Hose
Each hose connection intended for use by trained personnel (Class II and Class Systems
III) must be equipped with 30.5 m (100 feet) of 38 mm (1 ½ inches) listed line
of collapsible or non-collapsible fire extinguishers, fixed and ready for use. (NFPA 14, 2007)
14-14)
Location and Identification
The fire connections must be located and arranged so that the lines of
hoses can be attached to the inlets without interference from nearby objects, influenced
buildings, fences, posts, land, vehicles and other firefighter connections. The connections
firefighters must be located no more than 30.5 m (100 feet) from the nearest fire hydrant.
close connected to an approved water supply.
Minimum and Maximum Pressure Limits
Minimum Design Pressure for Hydraulically Designed Systems. The piping systems
Hydraulically designed vertical ones must be designed to provide the water flow rate.
required a minimum residual pressure of 6.8 bar (100 psi) at the output of the connection
65 mm (2 ½ inches) hose more hydraulically remote and 4.5 bars (65 psi) at the outlet
from the 38 mm (1 ½ inches) most hydraulically remote manquera station. (NFPA 14,
2007.p 14-23
Required Water Supply
Water supply must be allowed from the following sources:
A public supply system where the pressure and flow rate are adequate.
2. Automatic fire pumps connected to an approved water source in
compliance with NFPA 20, Standard for the Installation of Stationary Pumps
Fire Protection.
Hand-controlled fire extinguishers combined with pressure tanks.
4. Pressure tanks installed in accordance with NFPA 22, Standard for Tanks for Water Storage
Water for Private Fire Protection.
5. Manually controlled fire pumps operated by control devices
remote at each hose station, supervised in accordance with NFPA 72,
National Fire Alarm Code, at each hose station.
6. Gravity tanks installed in accordance with NFPA 22, Standard for Tanks for Water Storage
Water for Private Fire Protection. (NFPA 14, 2007, p. 29-30)