Inflammable Liquids

Inflammable Liquids

Report of Committee of National Fire Protection Association

THE Regulations for the Storage and Use of Fuel Oil and for the Construction and Installation of Oil-Burning Equipments for Domestic Use have been the subject of much discussion, and as now presented are believed suitable for adoption.

The Regulations for the Design and Construction of Concrete Fuel Oil Storage Tanks are the outcome of a conference between a sub-committee of this Committee and a sub-committee of a Main Commitee appointed by the Concrete Institute. Through some misunderstanding the Specifications reported by our sub-committee differ in a few respects from those reported by the sub-committee of the Concrete Institute, but this situation was not discovered in time to reach an agreement between the two committees.

In view of this, your Committee recommends the adoption of these Regulations as tentative, during the coming year. The Concrete Institute will not take action until next February, at their Annual Meeting, and there will therefore be an opportunity for further discussion and agreement before final action is taken by either association.

This Committee purposes during the coming year to revise the present Regulations for the Installation of Containers for Hazardous Liquids. This is necessary since they do not harmonize at some points with the Regulations for Fuel-Oil-Burning Equipments adopted last year. It is also possible that other changes in the subject matter may appear desirable. If any members of the Association have any suggestions, they will be received with due appreciation by the Chairman.


Note.—These regulations do not apply to oil burning devices employing a wick.

* Report of Committee on Inflammable Liquids.—Edward A. Barrier, Chairman; John S. Caldwell, Lawrence Daw, C. W. Hejda, M. F. Jones, K. G. MacKenzie, Van H. Manning, Hervey Mason. W. D. Matthews, H. E. Newell, I. Osgood, W. C. Plattt, A.M. Schoen, R. B. Soyez, F. J. T. Stewart, T, G. Toomey, R.O. Walker.


It is recognized that the safest and therefore the most desirable type of oil burning system for domestic use is that employing a pump to deliver the oil to the burner, and having all piping and the tops of all tanks located below the level of the burner base.

Systems employing gravity or pressure feed to the burner introduce a greater hazard and should not be permitted unless installed in full compliance with the following regulations.


The use of oil as fuel for domestic purposes is considered as more hazardous than the use of coal, wood and coke.

Oil used for fuel under these rules shall be a topped or distilled oil having a flash point of not less than 100° F., closed cup.

In determining the flash point, either the Elliot, Abel, Abel-Pcnsky or Tag Closed Testors shall be used, but the Tag Closed Tester (standardized by the United States Bureau of Standards) shall be authoritative in case of dispute. In such cases the-tests shall be made in accordance with the methods of tests as adopted by the American Society for Testing Materials.

An oil burning system shall consist of all equipment connected to the burner and located within the building, including auxiliary supply tank and provisions for filling same, piping, burner, and all accessories.

Only systems approved by the Inspection Department having jurisdiction shall be used.

Where these systems are used, their hazards shall be recognized and the following rules and precautions rigidly observed;

1. Capacity and Location of Storage Tanka

Storage tanks shall preferably be located outside underground, as provided in * Section 2, paragraph 17 of the preceding regulations. When located inside of a building and above ground the aggregate capacity of such storage tanks shall not exceed 275 gallons.

2. Material and Construction of Tanks

The material and construction of outside tanks shall be in accordance with the requirements of * Section 1, paragraphs 1 to 8 inclusive of the preceding regulations, I-pside storage and auxiliary supply tanks of more than 10 gallon capacity shall be constructed of galvanized steel, basic open hearth steel, or wrought iron of not less than No. 16 U. S. Gauge.

Here is a paper that deals with a mighty important subject. It takes up the discussion at a time when there is much being written. We would like to hear from our readers regarding their ideas-—Editor.

Auxiliary supply tanks of 10 gallons or less capacity may be constructed of brass, copper or galvanized plate of not less than No. 18 U. S. Gauge. Joints shall be made as specified for outside underground tanks in the *preceding regulations.

3. Gravity and Pressure Tanks

  1. Auxiliary supply tanks may be of the gravity or pressure type if. suitable automatic safeguards to prevent abnormal discharge of oil at the burner are provided. No such tank shall have a capacity sufficient for more than one day’s supply and in no case shall exceed 60 gallons.
  2. If located within a building, gravity tank shall not be within 5 feet, or pressure tank within 10 feet, measured horizontally from any fire or flame.
  3. Gravity or pressure tank shall be substantially and rigidly installed on incombustible supports in such a manner as to insure protection against mechanical injury.
  4. Tanks for systems under pressure shall be designed for six times the maximum working pressure and be tested and proven tight at twice the maximum working pressure; maximum working pressure shall not exceed 50 pounds. Tanks shall be provided with a reliable pressure gauge and an automatic relief valve piped to discharge outside of the building.
  5. Gauging devices or test wells, the breakage of which would permit the escape of oil or vapor within the building, shall be prohibited.

4. Filling of Auxiliary Tanks

  1. Auxiliary tanks shall be filled by pumping from storage tank, or if gravity or pressure tank contains the entire storage, fill pipe shall extend to and terminate outside the building, as provided in Section No. 1, paragraph 5 of preceding regulations, and in such cases tank shall be so installed that in case of overflow, oil will not enter building.
  2. Tank shall be provided with an overflow connection draining to storage tank. Overflow pipe shall be not less than one size larger than supply pipe from pump.
  3. The overflow pipe or gravity tank shall not be provided with valves or other obstructions; but overflow pipe of pressure tank and oil supply pipe shall be provided with inter-connected valves, so designed that the opening or closing of overflow pipe shall result similarly in oil supply pipe.

5. Pump

Oil pump used in filling auxiliary tank from the main storage tank shall be of approved type, secure against leaks, with check valves located as close to pump as convenient. Pumps shall be rigidly fastened in place.

6. Piping

  1. Standard, full weight, wrought iron, steel or brass pipe with substantial fittings shall be used and shall be carefully protected against mechanical injury in a manner satisfactory to the inspection department having jurisdiction. In all piping systems proper allowance shall be made for eypansion and contraction, jarring and vibration. All joints shall be made with litharge.

*This reference is to the fuel oil regulations for systems where a competent attendant is constantly on the premises. It is intended to bind both sets of regulations under the same cover, hence the wording used.

All piping shall be separated from electric wires not enclosed in approved conduit, raceways and armored cable, by some continuous and firmly fixed non-conductor creating a permanent separation, as provided in the National Electrical Code.

The use of tubing of any kind is prohibited.

  1. Supply pipe shall be not less than one-fourth inch in diameter, iron pipe size, and when oil is pumped to the burner, return pipes shall be at least the same size.
  2. Pipe connections to tanks shall be suitably reinforced, and proper allowance made for expansion and contraction, jarring and vibration.
  3. Openings for pipes through masonary walls below the ground level shall be made oil-tight and securely packed with flexible material.
  4. All connections shall be made perfectly tight with well fitted joints. Unions shall be used at burners to facilitate removal. All unions shall be of approved type, having comically faced joint, obviating the use of packing or gaskets.
  5. Piping shall be run as directly as possible, and in the case of pumping systems, so laid that if practicable the pipes are pitched back toward the storage tank without traps.
  6. Systems under pressure shall be designed for six times the working pressure and installation when complete shall be tested and proven tight at twice the maximum working pressure.

7. Valves

  1. Readily accessible valves shall be provided near each burner and also close to the auxiliary tank in the pipe line to burners.
  2. Control valves shall be of approved type provided with stuffing box of liberal size, containing a removable cupped gland designed to compress the packing against the valve stem and arranged so as to facilitate removal. Valve shall be designed to close against the supply, and to prevent withdrawal of stem by continued operation of the handwheel. The use of packing affected by the oil or heat is prohibited.

8. Burners

  1. The size of the orifice through which the oil is supplied to the burner shall be limited to furnish only sufficient oil for maximum burning conditions when the controlling valves are wide open.
  2. Valves shal be arranged so as not to enlarge the orifice.
  3. Burners containing chambers which allow the dangerous accumulation of gases, or oil conveying pipes or parts subject to intense heat or stoppage due to carbonization are prohibited.
  4. Burners shall be so designed as to permit of ready cleaning and not allow the leakage of oil.

9. Pilot Light

Automatic systems shall be so designed that the flame cannot be extinguished by operation of the automatic control valve, or a gas pilot light shall be provided in the combustion chamber.

10. Furnaces or Ranges

  1. Previous to the installation of the burner, the ash door of the furnace shall be permanently removed, or bottom ventilation otherwise provided to prevent the accumulation of vapors within the ash pit.
  2. Stoves or ranges originally designed for use of fuel other than oil should not be used in connection with oil burners unless spaces in which vapors might collect are adequately vented.
  3. No damper shall be permitted in the chimney uptake that may entirely shut off the passage of fumes or gases up the flue.
  4. No combustible material shall be stored within 10 feet of furnace door.

11. Fire Protection

(a) Any woodwork, wooden lath and plaster partition or other combustible material within 4 feet of the sides or back or 8 feet from the front of the furnace shall be covered with approved plaster board or other approved incombustible material. Abovve the furnace there shall be constructed a ceiling consisting of plaster board covered with sheet metal or cement plaster on metal lath; said ceiling shall extend 4 feet beyond the sides and back and 8 feet from the front.

At least a 36 inch clearance is necessary between top and sides of breeching and flues from ceiling, partitions and other combustible material, unless the breeching and flues are insulated with two to four inches of asbestos magnesia lagging or equivalent, in which case the clearance may be reduced to 18 inches.

(b) Near the furnace, and so located as tobe convenient for use in emergency, there shall be provided a hand fire extinguisher of approved type suitable for use on oil fires.

12. Instruction Card

A card giving complete instructions in regard to the care and operation of the system shall be permanently posted near the apparatus. Said card shall be placed under glass and framed.

13. Installation

Oil burning equipment shall be installed only by properly qualified mechanics experienced in this kind of work. It is recommended that systems be installed by the manufacturer.




1. Acceptability of Concrete Tanks

Concrete tanks may be used for the storage of fuel oil when the liquid is under 35° Baume.

2. Size and Location

The size of the tank and-its location including whether it shall be underground, above ground or inside a building shall conform in all respects with the current Regulations of the National Fire Protection Association for the Construction and Installation of Oil Burning Equipments.

3. Roof

AH tanks shall be built with a concrete roof. Roof shall be made gas tight at junction with walls and shall be constructed without unprotected openings.

4. Foundations

The tanks shall be set on firm well tamped earth, rock or other suitable foundation to guard against settlement. The foundations shall be constructed to provide full bearing for the tank bottom.

5. Pipe Con. actions, Fittings and Auxiliary Equipment

(a) The installation and arrangement of all pipe connections and fittings, including vent pipe, filling pipe, manhole covers, oil level indicating device, heaters and heating pipes, oil pipes and embankments or dikes shall conform in all respects with the current Regulations of the National Fire Protection Association for the Construction and Installation of Oil Burning Equipments.

(b) All pipes shall pass through the roof if possible. Where pipes pass through the tank there shall be flanged sections with a space of about 1 1/2 inches left between the flange and the concrete on each side of the wall. This pace shall be caulked later with litharge and glycerine or other satisfactory oil-proof material. It is also advisable to provide a ring projecting about 2 inches around the pipe sleeve to engage the concrete.

6. Supervision of Design and Construction

A competent, experienced designing and constructing engineer satisfactory to or representing the owners shall be responsible for the design of the tank. Detailed plans shall be submitted for approval to the Inspection Department having jurisdiction before the installation is started.

The work of construction shall be under the supervision of a competent engineer who shall superintend and inspect the placing of the concrete.



7. Loads

  1. Tanks shall be designed to provide for all internal add external loads. These include:

Full hydrostatic pressure of contents upon floor and walls.

  1. External hydrostatic pressure upon floors and walls.

Earth pressure on walls.

  1. Live and dead loads on roof.
  1. Column loads shall be distributed over a proper area by providing adequate footings and floor reinforcement.
  2. The hydrostatic pressure in the soil shall be considered equivalent to a fluid pressure of 62 1/2 lbs. per cubic foot for the full head of water.

Note—While the hydrostatic pressure in soil ia generally about 60 per cent of the full hydrostatic pressure, the greeater value is recommended as a factor of safety for unforseen conditions.

8. Temperature Reinforcement

Temperature reinforcement shall be placed in the walls and floor independent of other reinforcement, the steel ratio being not less than one-third of one per cent. The minimum range in temperature should be predetermined as a basis of calculation. Coarse aggregate shall consist of clean, hard, tough crushed rock, or pebbles graded in size, free from Vegetable or other organic matter and should contain no soft, flat or elongated particles. The size of the coarse aggregate shall range from 1 inch down, not more than 5 per cent passing a screen having four meshes per linear inch and no intermediate sizes shall be removed.

9. Thickness of Walls

The minimum thickness of walls shall be 8 inches at the top and 10 inches at the bottom in order to give sufficient space for spading.

10. Unit Stresses

  1. Steel in tension in the walls and floor shall be designed for a safe working stress of 10,000 lbs. per square inch whether in circumferential tension or in tension due to bending moments.
  2. In continuous or restrained members positive and negative tending moments shall be given equal consideration.
  3. In circumferential walls the thickness shall be based upon a maximum tensile strength in the concrete of 150 lbs. per square inch, but in no case shall be less than the minimum thickness given above. (Par. 9.)
  4. Working stresses in the conercte and steel for all cases not covered in (a) and (b) shall conform with the recommendations of the current “Report of the Joint Committee on Concrete and Reinforced Concrete.”



11. Materials of Construction

  1. The cement shall meet the requirements of the current standard specifications for Portland cement adopted by the American Society for Testing Materials and the American Concrete Institute. It shall be stored in a weathertight structure with the floor raised not less than 1 foot from the ground. Cement that has hardened or partially set shall not be used.
  2. Before delivery on the job, the contractor shall submit to the engineer in charge a 50 pound sample of each of the aggregates proposed for use. These samples shall be tested and if found to pass the requirements of the specifications, similar material shall be considered as acceptable for the work.
  3. Fine aggregate shall consist of natural sand or screenings from hard, tough crushed rock or pebbles, clean and free from any surface film or coating and graded from fine to coarse particles passing, when dry, a sieve having four meshes per linear inch. Fine aggregate shall not contain injurious vebetable or other organic matter as indicated by the Colorimetric Test, nor more than 7 per cent by volume of clay or loam. Field tests may be made by the engineer on fine aggregate as delivered at any time during the progress of the work. If there is more than 7 per cent of clay or loam by volume in one hour’s settlement after shaking in art excess of water the material represented by the sample shall be rejected.

Note—The Colorimetric Test may be applied in the field as follows: Fill a 12 ounce graduated prescription bottle to the 41 ounce mark with the sand to be tested. Add a 3 per cent solution of sodium hydroxide until the volume •f sand and solution, after shaking, amounts to 7 ounces. Shake thoroughly and let stand for 24 hours. The sample should then show a practically cplorless solution or at most a solution not darker than straw color.

  1. Crusher-run stone, bank-run gravel or mixtures of fine and coarse aggregates prepared before delivery on the work shall not be used because the ratio of fine to coarse material varies so widely as to lead* to concrete mixtures of greatly varying proportions.
  2. The water shall be free from oil, acid and injurious amounts of vegetable matter, alkali or other salts.

The reinforcing metal shall meet the requirements of the current standard specifications for billet steel reinforcement of the American Society for Testing Materials excepting that twisted square bars shall not be employed in the construction. Reinforcing shall be free from excessive rust, scale, paint or coatings of any character which will tend to reduce or destroy the bond.

12. Proportions of Concrete Mixture

  1. The unit of measure shall be the cubic foot. 94 pounds (one sack or one-fourth barrel) of Portland cement shall be assumed as 1 cubic foot.
  2. The concrete shall be mixed in a proportion by volume not leaner than 1 sack of Portland cement, 1 1/2 cubic feet of fine aggregate and 3 cubic feet of coarse aggregate.
  3. The method of measuring the materials for the concrete, including water, shall be one which will insure separate and uniform proportions of each of the materials at all times.

13. Method of Mixing

  1. All concrete shall be mixed by machine in a batch mixer of an approved type equipped with suitable charging hopper, water storage and a water measuring device which can be locked. The mixing plant shall be of sufficient capacity and power to carry out each pre-arranged operation without danger of delay during the process.
  2. The ingredients of the concrete shall be mixed to the required consistency and the mixing continued not less than one and one-half minutes after all materials are in the mixer and before any part of the batch is discharged. The mixer shall be emptied before receiving materials for the succeeding batch. The volume of the mixed material used per batch shall not exceed the manufacturer’s rated capacity of the drum.
  3. In no case shall aggregates containing frost or lumps of frozen material be used.
  4. The quantity of water used in mixing shall be the least that will produce a plastic or workable mixture which can be worked into the forms and around the reinforcement. Under no circumstances shall the consistency of the concrete be such as to permit a separation of the coarse aggregate from the mortar in handling. An excess of water shall not be permitted as it seriously affects the strength of the concrete and any batch containing such an excess shall be rejected.
  5. The retempering of mortar or concrete which has partially hardened, that is, remixing with or without additional materials or water shall not be permitted.

14. Depositing of Concrete

  1. Before beginning a run of concrete all hardened concrete or foreign material shall be completely removed from the inner surfaces of all conveying equipments.
  2. Before depositing any concrete, all debris shall be removed from the space to be occupied by the concrete, all steel reinforcing shall be secured in its proper location, all forms shall be thoroughly wetted except in freezing weather unless they have been previously oiled and all formwork and steel reinforcing shall be inspected and approved by the engineer.
  3. Concrete shall be handled front the mixer to the place of final deposit as rapidly as possible and by methods of transporting whih will prevent the separation of the ingredients. Chutes shall not be used. The concrete shall be deposited directly into the forms as nearly as possible in its final position so as to avoid rehandling. The piling up of concrete material in the forms in such manner as to permit the escape of mortar from the coarser aggregate shall not be allowed. Under no circumstances shall concrete that has partially set by deposited in the work.
  4. Where continuous placing of concrete in floor and walls is impracticable, the operations shall be in the following order:
    1. The concrete of all footings and floor, which shall be placed monolithically.
    2. The concrete of walls.
    3. The concrete of columns, if any.
    4. The concrete of roof.
  5. No break in time of over 45 minutes shall occur during any one operation. Between placing of columns and supported roof slabs an interval of at least 6 hours shall elapse to permit the settlement of concrete in the columns. In placing concrete in floors, it shall not be allowed to set up on exposed vertical faces where work is temporarily discontinued.
  6. In walls the concrete shall be placed in layers of not over 12 inches for the entire wall so that a monolithic structure will result. The concrete shall be thoroughly worked around the reinforcing material so as to completely surround and embed the same.
  7. If the placing of concrete is unavoidably interrupted by accident or otherwise, the pervious surface shall be roughened and washed clean with a hose, a mixture of 1:1 mortar slushed on uniformly before further concreting is done and the new concrete deposited immediately thereafter.
  8. When deposited in the forms, concrete shall be thoroughly spaded against the inner and outer faces of the forms so that it will densely compact and force out the trapped air and work back the coarser particles from the face of the forms.

Note—More and better work can be accomplished by using light wooden sticks one by two inches, planed smooth with sheet steel blade at lower end rather than with heavy spades. Enough laborers should be employed, spading continuously, to obtain satisfactory results.

  1. During freezing weather, the stone, sand or water or all three materials.shall be heated so that the concrete mixture will have a temperature of at least 60° F. After the concrete is deposted, precaution shall be taken to prevent freezing for at least 48 hours. Concreting shall not be begun when the temperature is below 15° F.

15. Forms

  1. The forms shall be of a good grade of lumber, planed to a uniform thickness and width, tongued and grooved tor walls, strongly made, and located or held in place either by exterior bracing or, on the outside of circular walls, by circumferential bands, so that no distortion allowing displacement of concrete is possible.
  2. Joints in forms shall be tight so that no mortar will escape. If forms are to be re-used, they shall be thoroughly cleaned. (A slush mixture of one-half petrolatum and one-half kerosene makes a good mixture for oiling forms.) The use of bolts or wires through the concrete shall be prohibited. All spreaders shall be removed.
  3. The forms shall not be removed until the concrete has sufficiently hardened so that no deflection or damage will result. In warm weather column and wall forms shall remain undisturbed for at least 48 hours and roof forms at least 7 days. In cold weather no predetermined rules can be made.
  4. Contractors equipped to handle the work with sliding forms may be permitted to do so provided the forms are left at one level until the concrete which will be exposed on raising them has hardened sufficiently to sustain the weight of the concrete above.

16. Details of Construction

  1. Reinforcing steel shall be cleaned of all mill and rust scales before being placed in the forms. All reinforcement shall be bent or curved true to templates, placed in its proper position as required by the plans and securely wired or fastened in place, well in advance of the concreting. Reinforcement shall be inspected and approved by the engineer before any concrete is deposited.
  2. Wherever it is necessary to splice the reinforcement, no lap-slice shall be less than 40 diameters. No two laps of adjacent rods shall be directly opposite each other in circular walls.
  3. All reinforcement shall be interconnected and grounded by an approved method as a protection against lightning. Any pipe passing through the tank shall be properly bonded to the reinforcement.
  4. If walls and floors are not deposited in one operation a suitable joint or dam shall be provided between the floor and walls. This can be made as follows: (1) Provide a recess in the floor to engage the wall and insert a galvanized iron strip at least 10 inches wide with joints riveted and soldered so as to form a continuous band on one side of the recess, or (2) place a 10-inch strip of deformed sheet metal 1 inch back from the inside form and engaging floor and wall euqally. After wall form is removed the 1-inch recess is to be plastered with a 1:1 1/2 mortar to make a 6-inch covered base.
  5. Unless the roof is insulated against temperature changes by sufficient earth cover or the reinforcing in walls and roof is designed to take care of temperature stresses likely to occur, an expansion joint shall be provided between the tops of walls and the bottom of roof slabs so that any expansion of the roof due to temperature will not transmit bending moment into the walls.
  6. In roof slabs where temporary stops are necessary they shall be made on the plans of least shear, that is, at the middle of beams or slabs.
  7. When tanks are being built in such locations that they may be subjected to hydraulic pressure through the soil, suitable provision shall be made to keep this pressure from acting on the fresh concrete until the latter has attained sufficient strength. If sheet piling or shores are used they shall be so placed that they will not pass through the walls.

17. Finishing

  1. The floors and roof shall be brought to grade with a straight edge or strike-board, finished with a wood float and troweled to a smooth surface as soon as possible after the concrete is deposited. As soon as the forms are removed, voids in walls, if any, shall be filled with a 1:1 1/2 mortar.
  2. The interior of the tank shall be oilproofed. This work shall be done only by persons familiar with the process. A bond guaranteeing the work for a term of years shall be furnished.
  3. Note—Oilproofing is deemed essential owing to the possibility of using the tank as a container for oils of various character.
  4. The tank shall be tested as soon as practicable in the opinion of the engineer by filling with water, and shall show no signs of leakage during a period of 7 days.
  5. Backfilling shall not be placed around the walls nor deposited on the roof until after the water test has been made, nor until a time when, in the opinion of the engineer in charge, it can be safely done.

No posts to display