АС 29-2B 7/30/97
786. EMERGENCY MEDICAL SERVICE (EMS) SYSTEMS, INSTALLATIONS, INTERIOR ARRANGEMENTS, AND EQUIPMENT.
a. Explanation. This paragraph pertains to EMS configurations and associated rotorcraft airworthiness standards. EMS configurations are usually unique interior arrangements that are subject to the appropriate airworthiness standards, FAR Part 29 or its predecessor CAR Part 7, to which the rotorcraft was certificated. No relief from the standards is intended except by § 21.21(b)(1) and exemption. EMS configurations are seldom, if ever, done by the original manufacturer.
(1) The FAA/AUTHORITY has not specified in the airworthiness or operating rules the minimum equipment for an EMS configuration. Whatever equipment is presented for evaluation and approval is subject to compliance with the airworthiness standards. Any equipment that is not essential to safe operation of the aircraft is evaluated for a "no hazard approval," i.e., it is optional equipment and may be approved provided the use, operation, and possible failure modes of the equipment are not hazardous to the aircraft. Safe flight, safe landing, and prompt evacuation of the rotorcraft, in the event of a minor crash landing, for any reason, are the objectives of the FAA/AUTHORITY evaluation of interiors and equipment unique to EMS.
For example, a rotorcraft equipped only for transportation of a nonambulatory person (a police rotorcraft with one litter) as well as a rotorcraft equipped with multiple litters and complete life support systems and two or more trained attendants/medical personnel may be submitted for approval. These configurations will be evaluated to the airworthiness standards appropriate to the rotorcraft certification basis.
(її) Transport rotorcraft should comply with many flightcrew and passenger safety standards which dictate features of the basic certified rotorcraft which are related to the interior arrangement, to the doors and emergency exits, and to occupant protection. Compliance with the airworthiness standards results in an emergency interior lighting system, placards or markings for doors and exits, exit size, exit quantity and location, exit access, safety belts, and possibly shoulder harnesses or other restraint or passenger protection means as a part of a rotorcraft type design. The features, placards, markings and "emergency" systems which are required as a part of the type design should be retained unless specific replacements or alternate designs are necessary for the EMS configuration to comply with the airworthiness standards.
(2) Many EMS configurations of transport rotorcraft are equipped with the following:
• Attendant/medical personnel seats which may swivel.
(її) Multiple litters, some of which may tilt.
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(iii) Medical equipment stowage compartments.
(iv) Life support and other complex medical equipment.
(v) Incubators for infants.
(vi) Curtains or other interior light shielding for the flightcrew compartment.
(vil) External loud speakers and search lights.
(vili) Special internal and external communication radio equipment.
b. Procedures.
(1) General.
Original type design information and criteria may or may not be available from the manufacturer. This may be "public," not proprietary, information that is pertinent for interior modifications. It may be appropriate to include "standard" features, placards, and markings for the rotorcraft type design by reference in the applicant's modification design data.
(ii) The EMS modification presented for approval usually contains equipment of one manufacturer's model or design. The type design of the modification will have features to power and restrain the equipment, maintain the rotorcraft systems integrity, and to otherwise protect the occupants. See Paragraph b(15) which refers to equipment substitution.
(2) Evacuation and Interior Arrangements. Access to the emergency exits/doors from any location in the cabin/compartment, access to and use of the exit/door opening means or release device, and the unobstructed area of the "standard" or type design exit are potential problems that should be addressed in the early design stage. Multilitter arrangements may be especially critical.
The operation or use of devices for locking the position of swivel seats, etc., and for rapid installation and removal of litters (incubators, etc.) should be labeled unless they are simple and obvious, and do not require exceptional effort. The design features of the device(s) and the seat and/or litter will influence the extent of information in any label necessary to insure proper and safe installation for routine use and for prompt evacuation when appropriate or necessary for the interior arrangement.
The requirement for labels or markings (instructions, etc.) that applies to operation of seat or litter features, release devices, etc., is not relieved even if trained attendants are necessary for an evacuation as discussed in Paragraph c(2)(v). Placards or instruction cards that contain evacuation procedures do not necessarily contain detail procedures Par 786 1243
for individual seats, litters, and so forth. Release devices that are simple and obvious and do not require exceptional effort are recommended. For example, a single central control for litter release would be preferred over multiple action release devices. Seats and litters which require multiple actions or steps to position or release for an emergency evacuation for the effect on achieving a rapid evacuation determines it is acceptable after minor crash landing may be acceptable if an evaluation determines it is acceptable.
(її) The passenger compartment or cabin should not be partitioned to impede access to the exits. A person seated in the compartment should have access to each exit in the compartment. All persons must be able or have provisions to rapidly clear (evacuate) the rotorcraft as specified in § 29.803(a). A demonstration or a "walk-through" of appropriate procedures may be necessary to assure the means and procedures are feasible and adequate. In certain designs and arrangements, an evacuation demonstration may be necessary to prove questionable interior and emergency exit/door arrangements.
(iii) Although not a standard, 90 seconds to clear the rotorcraft exits should be used as the time interval whenever an evacuation demonstration is dictated.
Attendants and the flightcrew, trained in the evacuation procedures, may be used to remove the litter patients. It is preferable for the patient to remain in the litter; however, the patient may be removed from the litter to facilitate rapid evacuation through the exit.
The patients are not ambulatory during the demonstration. The demonstration may be conducted in daylight with an upright rotorcraft. Exits on one side (critical side) should be used. Exits on the other side are blocked (possibly by a fire).
(iv) Special evacuation procedures and trained attendants may not be required for simple and obvious means of evacuation for a single litter. Procedures may be prominently displayed in durable markings, placards, cards, and condensed or summarized in the emergency procedures section of the Rotorcraft Flight Manual (RFM) or an EMS configuration RFM supplement.
(v) If any medical attendants are required for evacuation, the attendants should be trained in these procedures and listed in the Limitations section of the RFM or a supplement as a required crewmember. If attendants are not essential for safe rotorcraft operation or rapid evacuation, then an attendant is not a required crewmember.
(3) Restraint of Occupants and Equipment. The minor crash conditions specified in § 29.561(c) usually dictate all but the vertical (down and possibly up) load conditions. The flight and landing loads, such as +3.5g limit (flight) vertical override the minor crash loads when they are larger. See Paragraphs 218 and 335 of this AC for further information.
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7/30/97 АС 29-2B Whether seated or recumbent, the occupants must be protected as prescribed in § 29.785. Swivel seats and tilt litters may be used provided they are substantiated for the appropriate loads for the position selected for approval. Placards or markings may be used to assure proper orientation for flight, takeoff, or landing. The seats and litters should be listed in the type design data for the configuration. See Paragraph (b)(15) for substitutions.
(її) For recumbent occupants, harnesses, straps, a padded headboard, a diaphragm, or safety belts may be used if adequate for the forward and lateral loads of § 29.561(c). Harnesses/straps are recommended, however. When harnesses/straps are used, they should prevent the occupant from significant forward motion (4 g condition) that would remove the support from the head as well as the shoulder for "head down" motion. Infants in incubators should be similarly protected by padding and containment within the incubator and the incubator restrained for the load cases noted.
If the infant is strapped to a removable platform, the platform and infant should be properly restrained within the incubator for the load cases noted. The incubator should be listed in the type design data for the configuration.
(iii) Incubator materials are subject to the flammability standards of § 29.853. Evacuation procedures should include incubators if a part of the interior.
(iv) Galleys, medical supplies, and equipment compartments or modules should be restrained and the individual compartments must also contain the contents for the conditions noted in Paragraph (b)(3). Durable placards, decals, or markings should be used where appropriate to limit the maximum weight of any compartment and the whole module. Compartment latches having sufficient strength and displacement/engagement should be used to contain the compartment contents for the conditions noted. If necessary, a static load test or analysis should be employed to ensure the container/compartment remains intact and the latch does not disengage for the most critical conditions. Unrestrained (loose) contents in an individual compartment, in combination with similar compartments, should require use of a magnification factor with the conditions noted. Prudent design and location of compartments having heavy, unrestrained (loose) equipment will mitigate the potential effects of minor crash impact loads.
(4) Flammability Standards for Materials. Interior materials shall meet the flammability standards appropriate for the rotorcraft type design; § 29.853.
(ї) For rotorcraft certified prior to adoption of Amendment 29-17 (1978), the cabin materials shall be at least flash resistant and wall, ceiling linings, the covering of all upholstery, floors, and furnishings shall be at least flame resistant. Advisory Circular No. 23-2, Flammability Tests, dated August 20, 1984, contains test information about flash and flame-resistant material.
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(A) Flash-resistant material may be characterized as that not exceeding a 20-inch-per-minute (horizontal) burn rate. See AC 23-2 for further information.
(B) Flame-resistant material may be characterized as that not exceeding a 4-inch-per-minute (horizontal) burn rate.
(C) For incubators, transparencies must be flash resistant and fabric (padding, covers) straps, etc., must be flame resistant according to the standard.
(ii) For rotorcraft certified to Amendment 29-17 adopted in 1978, the materials shall be self-extinguishing as specified in the standards. For example, transparencies shall be self-extinguishing as prescribed in § 29.853(a)(2).
(III) Additionally, for rotorcraft certified to standards of Amendment 29-23 (1984), cushions of each passenger seat must have a "fire blocking layer" as prescribed in § 29.853(b).
(iv) The applicant is urged to use self-extinguishing materials regardless of the certification basis.
(V) For further information on materials, refer to Paragraph 358 of this AC. Advisory Circular 23-2, "Flammability Tests," dated August 20, 1984, also contains information about flash-resistant and flame-resistant material tests.
(5) Exit Signs/Markings and External Markings. The approved exits require certain signs, instructions, and identification. The rotorcraft type design contains the required data. The maintenance manual and the RFM should also contain this information. See Paragraph 342 of this AC for more information. Alternates may be approved which then become part of the applicant's type design data. All U.S.
transport rotorcraft presently in service should have an emergency interior lighting system to comply with § 29.811(f). (Refer to the certification basis of the rotorcraft.)
(6) Interior or "Medical" Lights. The view of the flightcrew must be free from glare and reflections that could cause interference. Curtains that meet flammability standards may be used. Complete partition or separation of the crew and passenger compartment is not prudent. Means for visual and oral communication are usually necessary. Paragraph 328 of this AC concerns pilot visibility.
(7) Patient Interference. When passengers or patients are located in close proximity to the pilot and the primary flight controls of the rotorcraft, a guard or shield should be installed or the patient restrained to prevent inadvertent or potential convulsive interference with safe operation of the rotorcraft. The guard may be a part of the rotorcraft interior features. In addition, rapid evacuation should be assured if a guard is used.
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(8) External Devices.
(i> Search lights, loud speakers, baggage pods, etc., may be installed on the underside of or elsewhere on the rotorcraft. The strength of the attachments shall be substantiated for the flight and landing conditions, and for the minor crash conditions where applicable. Pilot visibility should not be affected adversely by lights or light reflection.
(ii) The device or pod located on the underside of the rotorcraft should not contact a level landing surface after "limit landing load" deflection of the landing gear. The gear should deflect without causing damage to the device. For example, if the limit landing load deflection is 8 inches, the device shall have at least 8-inch clearance to avoid contact with the landing surface or have an equivalent feature of design. The physical characteristics of the rotorcraft design dictate the necessary clearance for landing gear deflection. In addition, the device should be designed and located on the rotorcraft to preclude penetration of the device into a critical area of the fuselage. For example, the device should be located to minimize the potential of penetration into a fuel line, fuel cell, primary control tube, or occupant seat for any reason.
(ill) A flight evaluation is necessary to determine the effects of the device or devices on the rotorcraft flight characteristics and flightcrew night visibility.
(9) Miscellaneous. Various paragraphs in this AC contain guidance for the standards cited in the reference list (reference c(1)). These paragraphs should provide insight into designing an EMS configuration that would be acceptable under the standards.
(10) Oxygen. EMS oxygen installations are supplied by either liquid or gaseous oxygen. Both types of systems are discussed in this paragraph.
Liquid Oxygen.
(A) System General Description. This section covers specific requirements for liquid oxygen systems. Most liquid oxygen systems in use are installed in military aircraft and, as a result, much of this material is based on experience with these systems. A rotorcraft liquid oxygen system should be comprised of a liquid oxygen converter, tubing, fittings, quantity gage, heat exchangers, and appropriate pressure and flow control components as shown in Figures 786-1 and 786-2. The installation may provide for replenishing the liquid oxygen supply by use of a quick-removable converter or, in the case of a fixed installation converter, by providing external access for connection to a portable service trailer. More complicated systems such as those with multiple converter assemblies are not discussed here since installation of those systems are not envisioned in rotorcraft at this time.
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(B) System Components. All components should be aircraft qualified and suitable for use in an EMS rotorcraft application.
(1) Liquid Oxygen Converter. A liquid oxygen converter assembly is a self-powered system for the storage of liquid oxygen and for its conversion to gaseous oxygen when required. A principal part of the converter assembly is a vacuum insulated container. Pressure relief valves should be provided to allow the escape of gas generated when oxygen is not being expended in the supply line. Oxygen losses from a converter assembly vary from 5 to 20 percent per 24 hours depending on the size of the container, its installation environment, and so forth. Aircraft qualified and approved converters suitable for EMS rotorcraft use are available in either 5- or 50-liter capacities. Size selection should be determined by flow rate and duration requirements. Performance characteristics of each converter size are available from the manufacturer.
(2) Shutoff Valve Assembly. This valve shall be accessible to a flightcrew member and be mounted in the supply line on or as close as possible to the outlet of the converter. This valve provides for the confinement of the remaining supply of liquid oxygen to the converter in the event of an emergency. Since the system pressure is low, the use of an electrically actuated shutoff valve is satisfactory to accomplish this function. In some installations, where the evaporating coil is immediately adjacent to the converter, a flow fuse has been used to accomplish this function. Use of a flow fuse must be supported by a system fault analysis and testing to show maximum normal flow will not result in nuisance trips, and reliable trips will be provided for malfunction conditions resulting in excess flow.
(3) Eiller Valve. Some designs combine this function with the build-up and vent valve assembly as shown in Figure 786-2.
(4) Build-up and Vent Valve Assembly. This valve is positioned in the "vent" position when the system is being filled with oxygen and in the "build-up position at other times. Some designs combine this function with the filler valve as shown in Figure 786-2.
(5) Pressure Build-up Coil Assembly and Pressure Closing Valve.
With the build-up and vent valve in the "build-up" position gas that is formed is allowed to apply pressure to the liquid to provide adequate flow through the check valve to the evaporating coil assembly. A connection to a pressure relief valve is also provided.
(6) Evaporating Coil Assembly. This is provided to convert the liquid oxygen into a gaseous form. The evaporating coil assembly should be of sufficient capacity to maintain the design flow quantity to the dispensing regulators at a temperature within +10 and -20° F of cabin ambient temperature. MIL-D-19326G contains a discussion of installation considerations for this unit.
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Vent Line. Gaseous oxygen escapes through this line. At the conclusion of the fill operation, liquid oxygen will flow overboard in a steady stream from this line to indicate the container is full of liquid oxygen. The vent line should be located to drain overboard at the bottom of the rotorcraft fuselage. Flow from the overboard vent should be directed so as not to create a hazard for personnel and not allow liquid oxygen to impinge on the rotorcraft. The vent lines should be insulated to prevent frosting and sweating if they pass over equipment which will be harmed by water dripping from the lines, or drip pans should be installed under the lines. There should be no hydrocarbon fills or drains, forward or above, in proximity to the vent outlet.
(8) Regulator. A regulator should be installed in the supply line downstream from the heat exchanger. The regulator should reduce the liquid oxygen converter operating pressure to a supply pressure of 50 pounds per square inch gauge (PSIG) to be compatible with the normal operating pressure of medical oxygen equipment.
(9) Elow Control Valve. This valve provides a calibrated flow of gaseous oxygen from an operating supply of 50 + 5 PSIG. A valve whose proof pressure is specified at 80 PSIG and has a burst pressure rating of 350 PSIG would be considered satisfactory.
(10) Check Valve. This valve prevents gaseous oxygen in the supply system from backing up into the liquid oxygen in the container and increasing the vaporization rate of the liquid oxygen by exposure to the gas. This valve is normally an integral part of the liquid oxygen converter assembly.
(11) Quantity Indicators. A quantity indicator should be installed at the appropriate rotorcraft crew station to permit monitoring of the liquid oxygen supply.
The indicator when installed in the rotorcraft should indicate the amount of liquid oxygen in the converter. Adequate clearance should be provided for the indicator connectors so that they can be readily disconnected by servicing personnel. Provisions should be made for the storage of the rotorcraft connectors to the liquid oxygen converter when they are disconnected. Liquid oxygen quantity indicating equipment is available in three types: capacitance gauging, electro-mechanical transducer indication, and differential pressure type indication.
(12) Pressure Relief Valves. Pressure relief valves are provided to vent overboard through the overboard vent system any excess pressures developing within the system.
(13) Lines. Lines should be either solid tubing or flexible hoses.
Examples of acceptable solid tubing are aluminum alloy conforming to AMS 4071 or corrosion resistant annealed steel (304) confirming to MIL-T-8506. Flexible hoses should be used for rotorcraft system connections to removable converters and to other Par 786 1249
АС 29-2B 7/30/97 applications where relative movement may occur. Flexible hoses should be wire-braid-covered bellows or wire-braid-covered tetrafluoroethylene. Flexible hose conforming to MS90457 or MS24548 would be considered satisfactory. MS90457 hose is flexible to -297° F (-183° C), and MS24548 hose is flexible to -65° F (-54° C).
Synthetic lines such as plastic, nylon, or rubber should not be used for lines subjected to continuous pressure, or for application where the line will not be visible. Lines that are not visible are those that are located behind liners or in the walls of the fuselage.
(14) Fittings. If in contact, dissimilar metals should be suitably protected against electrolytic corrosion. Line assemblies should be terminated with "B" nuts or a similar manufactured terminating connection. Universal adapters (AN 807) or friction nipples used in conjunction with hose clamps should be avoided for use in pressurized systems.
(15) Drain Valve. Systems that have permanently installed containers should include a drain valve located to allow for complete draining of the liquid oxygen container. An acceptable drain valve would be one in accordance with MK-V-25962 that is suitably capped. A cap in accordance with AN 929-5 with a permanently attached chain is a suitable cap.
(16) Low Pressure, Low Level Warning System. It is recommended that provisions be included in the system to alert the appropriate aircraft crew member that the level of the oxygen supply has reached some low level. It is recommended that low level be actuated when less than 10 percent of the full container capacity is available. If low system pressure is also monitored, the low pressure valve selected should be such that any drop in supply line pressure upon inhalation should not activate the low pressure warning function.
(C) Component Installation. The following are typical installation considerations that should be addressed when designing the oxygen system.
(1) Location. The oxygen equipment, lines, and fittings should be located as remotely as practicable from sources of flammable fluids, high heat and electrical items, fuel, oil, hydraulic fluid, batteries, exhaust stacks, manifolds, and so forth. Oxygen lines should not be grouped with lines carrying flammable fluids. If possible, converters should not be in line with the plane of rotation of a turbine. System components should not be installed in an environment that will exceed the temperature limit of the component, and no part of the system should be installed in an area that will exceed 350° F (176° C). To minimize loss due to heat, the liquid oxygen converter should not be located near equipment that dissipates a high quantity of heat.
(2) Converter Mounting. The oxygen container should be readily accessible to servicing personnel. If the container is not removable for servicing, the filler should be external to the aircraft with adequate contamination protection.
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Mounting provisions for the converter and plumbing to the evaporating coil assembly should include a drain pan with an overboard drain.
(3) Elexible Hoses. Hoses should be of sufficient length to provide unstressed connections and be protected against chafing on surfaces or objects which may damage the wire covering. The bend radius imposed on the hoses by the installation and during remove and replace actions should not be less than the minimum established by the hose specifications.
(4) Lubricants. No lubricants should be used on liquid oxygen pipe fittings. MIL-T-27730 Teflon tape may be used on male pipe fittings when required.
Teflon tape should not be used on flared tube fittings, straight threads, coupling sleeves, or on the outer side of tube flares. None of the tape should be allowed to enter the inside of a fitting. Krytox fluorinated grease by E... Dupont De Nemours and Company, or an equivalent, may be used sparingly on seals.
(5) Tubing Routing and Mounting. There should be at least 2 inches of clearance between the oxygen system and flexible moving parts of the rotorcraft.
There should be at least a ½-inch clearance between the oxygen system and rigid parts of the rotorcraft. The oxygen system tubing, fittings, and equipment should be separated at least 6 inches from all electrical wiring, heat conduits, and heat emitting equipment in the rotorcraft. Insulation should be provided on adjacent hot ducts, conduits, or equipment to prevent heating of the oxygen system. In routing the tubing, the general policy should be to keep total length to a minimum. Allow for expansion, contraction, vibration, and component replacement. All tubing should be mounted to prevent vibration and chafing. This should be accomplished by the proper use of rubberized or cushion clips installed at 24-inch intervals (copper) or 36-inch intervals (aluminum) and as close to the bends as possible. The tubing, where passing through or supported by the rotorcraft structure, should have adequate protection against chafing by the use of flexible grommets or clips. The tubing should not strike against the rotorcraft structure during vibration and shock encountered during normal use of the rotorcraft.
(6) System Marking. The rotorcraft should be permanently and legibly marked, as applicable, in the locations specified below (a minimum letter height of ¼ inch is recommended):
Adjacent to the overboard vent opening:
CAUTION
LIQUID OXYGEN VENT (I) On outside surface of filler box cover plate:
LIQUID OXYGEN (BREATHING) FILL ACCESS Par 786 1251
(iii) On underside surface of filler box cover plate:
CAUTION - KEEP CLEAN, DRY, AND FREE FROM OILS
(iv) In prominent place when filler box is open, preferably near liquid oxygen drain valve:
DO NOT OPEN DRAIN VALVE UNTIL DRAIN HOSE
AND DRAIN TANK ARE CONNECTED (V) Other placards, such as one at the converter cautioning about the presence of liquid oxygen, may also be appropriate.
(Z) Other installation criteria are given in Chapter 6, AC 43.13-2A, Acceptable Methods, Techniques, and Practices-Aircraft Alterations, dated June 9, 1977, and should be given full consideration.
(D) Precautions. The referenced SAL report contains precautions peculiar to a liquid oxygen installation, and this material should be reviewed. It should also be emphasized that liquid oxygen equipment and the aircraft being serviced must be electrically grounded during servicing to prevent an accumulation of static electricity and discharge. The following considerations are included for special emphasis:
(1) System Cleanliness. The completed installation should be free of oil, grease, tuels, water, dust, dirt, objectionable odors, or any other foreign matter, both internally and externally prior to introducing oxygen in the system.
(2) Closures. Lines which are required to be disconnected, due to the location of the converter within the rotorcraft during rotorcraft maintenance checks or overhaul, should be capped to prevent materials which are incompatible with oxygen from entering the system when the system integrity is broken. Caps which introduce moisture and tapes that leave adhesive deposits shall not be used for these purposes.
All openings of lines and fittings shall be kept securely capped until closed within the installation.
(3) Degreasing. All components of the oxygen system should be procured for oxygen service use in an "oxygen clean" condition. Parts of the oxygen system, such as tubing, not specifically covered by cleaning procedures should be degreased using a vapor phase trichloroethane degreaser. Ultrasonics may be used in conjunction with vapor phase degreasing for the cleaning of components.
(4) Purging. The system should be purged with hot, dry
99.5 percent pure oxygen gas in accordance with the manufacturers recommendations after:
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Initial assembly of the oxygen system; and
(i) After system closure whenever the oxygen system pressures have been depleted to zero, or the system has been left open to atmospheric conditions for a period of time or is opened for repairs.
(5) Maintenance and Replacement. All parts of the oxygen system should be installed to permit ready removal and replacement without the use of special tools. All tubing connections and fittings should be readily accessible for leak testing with a leak test compound formulated for leak testing oxygen systems and for tightening of fittings without removal of surrounding parts.
(il) Gaseous Oxygen.
(A) General. This guidance is intended to supplement the existing guidance in AC 43.13-2A, Chapter 6. If there are any differences within the two AC's, this guidance shall prevail since it pertains specifically to Part 29 requirements.
(B) System Components.
(1) High Pressure Cylinders. Many installations utilize hospital type cylinders rather than aviation type cylinders. A concern with the hospital type cylinders is the yoke and the hard plastic washer that is commonly used with these cylinders. It is very difficult to properly attach these yokes since the rotorcraft provides a high vibration environment and no positive lock is provided. Leaks are a continuous problem with this configuration. Yokes are available for these bottles that provide for a positive lock. Improved washers that provide for a good elastomeric seal and include a metal ring to limit crushing the washer are also available. If the hospital type bottles are to be used, only the moditied yokes and improved seals should be considered for future installations. The preferred cylinder is the aviation type cylinder with the integral shut-off valve and regulator. All cylinders should be DOT approved.
(½) LInes.
(1) General. Any lines that pass through potential fire zones should be stainless steel.
(Ш) High Pressure. Use of high pressure lines may be necessitated by the use of a pressure regulator that is remote from the cylinder. The intent is to locate the regulator as close as physically possible to the cylinder, and to minimize the use of fittings. Lines of 6-inch lengths are encouraged with 18-inch lengths being the maximum in unusual circumstances. Lines made of stainless steel are recommended.
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