Propane (C₃H₈) is a liquefied petroleum gas (LPG) that exists in liquid form when stored under pressure in a tank. At atmospheric pressure, it immediately vaporizes into gas. This characteristic is fundamental to understanding how propane systems work in recreational vehicles (RVs).
As a recreational vehicle service technician, you must master the following Canadian standards:
CSA B149.1 – Natural Gas and Propane Installation Code (installation portion)
CSA B149.2 – Propane Storage and Handling Code (storage and handling portion)
CSA Z240.2.1 – Standard for Recreational Vehicles (construction requirements)
CSA Z240.4 – Requirements for Gas Systems in Recreational Vehicles
CSA B149.1 is the primary reference for the installation, modification, and repair of propane systems in RVs. The rules applicable to RVs are specifically identified in Section 6 of this standard.
Physical and Chemical Properties of Propane
Essential Characteristics
Property
Value
Chemical formula
C₃H₈
Liquid density
0.51 kg/L (at 15 °C)
Gas density (vs air)
1.52 (heavier than air)
Boiling point
−42 °C (at atmospheric pressure)
Higher heating value
25.3 MJ/m³ (gas); 46.4 MJ/kg (liquid)
Lower explosive limit (LEL)
2.1% (volume in air)
Upper explosive limit (UEL)
9.5% (volume in air)
Auto-ignition temperature
493 °C
Vapour pressure at 20 °C
830 kPa (approx. 120 psi)
Practical Implications for the Technician
Because propane is heavier than air, any leak will accumulate at the lowest point of the vehicle. This is why propane detectors in RVs must be installed near the floor, unlike carbon monoxide detectors, which are placed higher up.
Vapour pressure varies considerably with temperature. At −40 °C, the pressure is nearly zero; at 40 °C, it reaches approximately 1,400 kPa. This variation explains why regulators must be capable of handling a very wide range of inlet pressures.
Commercial propane is odorized with ethyl mercaptan to enable olfactory detection of leaks. The olfactory detection threshold is approximately 0.1% of the LEL (i.e., 0.002% of air volume).
Components of an RV Propane System
The Tank
Propane tanks for RVs are manufactured in accordance with CSA B339 (gas cylinders) or ASME (American Society of Mechanical Engineers) for fixed tanks. Two main configurations exist:
23.Portable cylinders (typically 20 lb or 30 lb) – mounted on the tongue or front wall of the RV
24.Fixed ASME tanks – installed under the floor or in a dedicated compartment
Each tank must include the following components:
Safety relief valve – calibrated to open at 2,400 kPa (350 psi) for DOT cylinders
Level indicator (gauge) – rotary or float type
Main shut-off valve (service valve)
Valve protector – for portable cylinders
The Regulator
The regulator is one of the most critical components. Its function is to reduce tank pressure (which varies with temperature) to a constant operating pressure.
Two stages of regulation:
First stage: reduces tank pressure (up to 1,400 kPa) to approximately 340 kPa (50 psi)
Second stage: reduces pressure from 340 kPa to the operating pressure of 2.74 kPa (11 inches water column) for most appliances
Some regulators are single-stage (a single unit that performs all the reduction). In RVs, two-stage regulators or integral regulators (two stages in one housing) are used almost exclusively.
Standard service pressure: 2.74 kPa (11 in water column) for domestic and RV appliances. Some high-efficiency appliances may require 3.73 kPa (15 in water column) – always check the appliance nameplate.
The Piping
Propane piping in RVs must be copper type K or L (seamless), black steel, or certified flexible tubing. Fittings must be:
Threaded (steel) – with a sealant approved for gas
Compression – only with solid brass ferrules, never stainless steel
Strictly prohibited: compression fittings with split-ring ferrules are not permitted in propane systems. Soft-soldered (tin) fittings are also prohibited.
The piping diameter depends on the equivalent length of the run and the total load in BTU/h of the appliances. The following table gives approximate capacities for type L copper:
Outside diameter (in)
Max length (ft) for 100,000 BTU/h
Max length (ft) for 50,000 BTU/h
3/8
15
40
1/2
40
100
5/8
70
180
3/4
130
350
These values are indicative; always consult the CSA B149.1 tables for precise calculations.
The Appliances
Propane appliances in an RV typically include:
Stove (range with oven)
Oven (often combined with the stove)
Refrigerator (absorption type, operates on propane, 120 V, or 12 V)
Water heater (6 or 10 gallons)
Furnace (forced-air heating)
Outdoor grill (optional)
Generator (on certain models)
Each appliance must have a nameplate indicating:
The model and serial number
The type of gas (propane only)
The required inlet pressure
The BTU/h rating (input and output)
Certifications (CSA, ULC, etc.)
Installation Rules per CSA B149.1
Section 6 – Recreational Vehicles
Section 6 of CSA B149.1 contains the specific rules for RVs. Here are the essential points for the exam:
Rule 6.1 – General: All appliances installed in an RV must be CSA-certified and installed in accordance with the manufacturer's instructions and the requirements of CSA Z240.4.
Rule 6.2 – Cylinder Location:
Portable cylinders must be mounted on the tongue or front wall, outdoors
They must be securely fastened and protected against damage
Cylinders must never be installed inside the vehicle, even in a ventilated compartment
Cylinder compartments must be vented to the outside and must not communicate with the RV interior
Rule 6.3 – Piping:
Piping must be supported at maximum intervals of 1.2 m (4 ft) for copper
It must be protected against abrasion at points where it passes through partitions
Fittings must be accessible for inspection
No fittings are permitted within the thickness of a wall, floor, or ceiling
Rule 6.4 – Regulators:
The regulator must be installed outside the RV or in a compartment vented to the outside
The regulator vent must be oriented downward and protected against water and insect entry
The regulator must be accessible for servicing
Rule 6.5 – Leak Test:
After any installation or modification, the system must be subjected to a leak test at a pressure of 350 kPa (50 psi) for at least 10 minutes
The pressure drop must not exceed 0.7 kPa (0.1 psi) during the test period
The test must be performed with compressed air or an inert gas (never oxygen)
Rule 8-200 (Cross-Reference)
Although Rule 8-200 is associated with the Canadian Electrical Code, Part I (verification of electrical installations), it is often cited in the RV context because it deals with the initial verification of installations. For propane, the equivalent verification is the mandatory leak test before commissioning.
Testing and Diagnostic Procedures
Complete Leak Test
Standard procedure:
90.Close all appliance valves
91.Isolate the tank by closing the main valve
92.Connect the pressure gauge to the system (at the regulator or at a test point)
93.Pressurize the system to 350 kPa (50 psi) with compressed air
94.Wait 10 minutes for thermal stabilization
95.Record the initial pressure
96.Wait an additional 10 minutes
97.Record the final pressure – the drop must not exceed 0.7 kPa (0.1 psi)
Interpreting results:
Pressure drop
Diagnosis
0 to 0.7 kPa
System is tight – acceptable
0.7 to 3.5 kPa
Minor leak – locate with soap solution
> 3.5 kPa
Major leak – relieve pressure, inspect visually
Leak Detection
Soap solution method:
Apply a soapy water solution (or commercial product) to all fittings
Observe for bubble formation – growing bubbles indicate a leak
Never use a flame to detect a leak
Electronic detector:
Calibrate the device according to the manufacturer's instructions
Move the probe slowly (2.5 cm/s) along the fittings
Check areas of high accumulation (low compartments)
Regulator Pressure Verification
Equipment: water column manometer (magnehelic gauge) or digital manometer
Procedure:
112.Close all appliances
113.Connect the manometer to the regulator test port or the nearest fitting
114.Open the tank valve
115.Allow the pressure to stabilize (30 seconds)
116.Read the pressure – it must be 2.74 kPa (11 in water column) ± 10%
Flow test:
Open all appliances simultaneously
The pressure must not drop more than 1.25 kPa (5 in water column) below static pressure
If the drop is excessive, check: the regulator, piping diameter, obstructions
Essential Calculations
Calculating Total Load
The total load of a system is the sum of the flow rates of all appliances:
Total load (BTU/h) = Σ (flow rate of each appliance)
Example:
Appliance
Flow rate (BTU/h)
Stove (4 burners + oven)
65,000
Refrigerator
1,500
Water heater
32,000
Furnace
35,000
**Total**
**133,500**
Calculating Equivalent Length
Equivalent length accounts for pressure losses in fittings and elbows:
Equivalent length = Actual length + (number of elbows × 2.5 ft) + (number of tees × 5 ft) + (number of valves × 1 ft)
Example: A 20 ft run with 4 elbows and 2 tees:
EL = 20 + (4 × 2.5) + (2 × 5) = 20 + 10 + 10 = 40 ft
Cylinder Autonomy
Autonomy (hours) = (Cylinder content in BTU) ÷ (Total load in BTU/h)
A 20 lb cylinder contains approximately 430,000 BTU (20 lb × 21,500 BTU/lb).
Example: With a load of 30,000 BTU/h:
Autonomy = 430,000 ÷ 30,000 = 14.3 hours
Safety and Best Practices
Cylinder Handling
Always transport cylinders in the upright position
Never leave a cylinder in a closed vehicle exposed to sunlight
Check the test date (stamping) – DOT cylinders must be requalified every 10 years
Never fill a cylinder beyond 80% of its capacity (thermal expansion margin)
Compartment Ventilation
Compartments containing cylinders or regulators must have:
A ventilation opening of at least 650 mm² (1 in²) at the bottom
A ventilation opening of at least 650 mm² (1 in²) at the top
These openings must communicate directly with the outside
Propane Detectors
RVs must be equipped with a propane detector certified to CSA 6.29, installed:
Near the floor (propane is heavier than air)
Within 1.5 m of sleeping areas
Away from direct air currents (ventilation outlets, doors)
The detector must be tested each time the RV is used and replaced according to the manufacturer's recommendations (typically 5 to 7 years).
Standards and Certifications
Key Standards and Organizations
Standard
Title
Application
CSA B149.1
Natural Gas and Propane Installation Code
Installation, modification, repair
CSA B149.2
Propane Storage and Handling Code
Storage, filling, handling
CSA Z240.2.1
Recreational Vehicles – Construction Requirements
Structure, safety, systems
CSA Z240.4
Requirements for Gas Systems in Recreational Vehicles
Propane systems specific to RVs
CSA B339
Cylinders for Gas – General Requirements
Cylinder manufacturing and requalification
CSA 6.29
Liquefied Petroleum Gas Detectors
Propane detectors for RVs
Appliance Certifications
Each appliance must bear the certification mark of an accredited organization:
CSA (Canadian Standards Association)
ULC (Underwriters Laboratories of Canada)
cUL (UL with Canadian marking)
Certification attests that the appliance has been tested and approved for propane use in an RV.
Preventive Maintenance
Periodic Checks
At every service call:
Visual inspection of all piping (corrosion, abrasion, supports)
Verification of cylinder fastening
Test of the propane detector (test button)
Inspection of flexible hoses (cracks, discoloration, swelling)
Annually:
Complete leak test of the system
Regulator pressure verification (static and dynamic)
Burner inspection (blue flame, carbon deposits)
Check of compartment ventilation openings
Visual test of the safety relief valve operation
Signs of Malfunction
Symptom
Probable cause
Corrective action
Yellow flame
Clogged burner, lack of primary air
Clean the burner, adjust air
Flame blow-off
Pressure too high
Check/adjust the regulator
Weak flame
Pressure too low, undersized piping
Check the regulator, obstructions
Gas odour
Leak
Shut off gas, perform leak test
Ignition difficulty
Clogged orifice, faulty thermocouple
Clean, replace
Common Pitfalls to Avoid
184.Confusing test pressure and service pressure: the leak test is done at 350 kPa (50 psi), but the service pressure is 2.74 kPa (11 in water column). Never put an appliance under 350 kPa – appliances are designed for 2.74 kPa only.
185.Using Teflon tape (PTFE) on threaded fittings: Teflon tape is prohibited on propane fittings. Use only a paste-type sealant approved for gas.
186.Forgetting compartment ventilation: any compartment containing propane components must be vented to the outside, at both the top AND bottom.
187.Installing a propane detector high up: since propane is heavier than air, the detector must be near the floor.
188.Neglecting cylinder test dates: a cylinder whose test date has expired must be removed from service and requalified.
189.Mixing up pressure units: 11 in water column = 2.74 kPa = 0.4 psi. Never mix units in your calculations.
190.Using a compression fitting with a split-ring ferrule: prohibited in propane systems. Use solid brass ferrules or brazed fittings.
191.Forgetting the thermal stabilization period: pressure varies with temperature. Wait 10 minutes before taking the initial reading of the leak test.
192.Not checking the nameplate: each appliance has specific pressure and flow requirements. Never assume – always verify.
193.Closing the tank valve before turning off appliances: the correct sequence is: turn off the appliances, THEN close the tank valve.
Summary
Propane is heavier than air and accumulates at floor level – detectors are placed near the floor
The standard service pressure is 2.74 kPa (11 in water column) for RV appliances
CSA B149.1 (Section 6) governs the installation of propane systems in RVs
The leak test is performed at 350 kPa (50 psi) with a maximum drop of 0.7 kPa (0.1 psi) over 10 minutes
Cylinders must be requalified every 10 years (DOT stamping)
The maximum fill level is 80% of cylinder capacity
Compression fittings with split-ring ferrules and Teflon tape are prohibited
Copper piping must be type K or L, brazed with silver alloy
Compartments containing propane components must be vented to the outside (top and bottom)
Each appliance must be CSA-certified and bear a legible nameplate
The propane detector must be certified to CSA 6.29 and tested regularly
The total system load is calculated by summing the BTU/h ratings of all appliances
The equivalent piping length must include losses from fittings and elbows
Exam Tips
211.Memorize the key values: 2.74 kPa, 350 kPa, 0.7 kPa, 80%, 10 years, −42 °C (boiling point), 1.52 (density vs air).
212.Understand the principles, not just the numbers: why propane is heavier than air, why pressure varies with temperature, why fittings must be brazed.
213.Know how to identify the standards: B149.1 = installation, B149.2 = storage, Z240.2.1 = RV construction, Z240.4 = RV gas systems.
214.Practice the calculations: total load, equivalent length, cylinder autonomy, allowable pressure drop.
215.Visualize the diagrams: be able to trace the gas path mentally from the tank to the appliances, identifying each component.
216.Review the prohibitions: what is prohibited is as important as what is permitted (Teflon, split-ring ferrules, soft solder, oxygen for testing, detector placed high).
217.Connect the concepts: the density of propane explains the placement of detectors, compartment ventilation, and handling precautions.
218.Use the questioning method: for each rule, ask yourself "why does this rule exist?" – the answer is almost always related to safety.
