Oklahoma Natural Gas Journeyman

Both operate with positive vent static pressure, but Category III has a vent gas temperature that avoids excessive condensate production while Category IV produces excessive condensate (Categories I and II are nonpositive pressure).

The Standard Method requires 50 cubic feet per 1,000 Btu/h of appliance input rating, while the known air-infiltration-rate method divides a constant (21 ft³ or 15 ft³) by the ACH value for each 1,000 Btu/h of input.

In the known air-infiltration-rate method, fan-assisted appliances use a numerator of 15 ft³ while appliances other than fan-assisted use 21 ft³, each divided by ACH per 1,000 Btu/h of input.

Under the two-permanent-openings method, horizontal ducts require 1 square inch per 2,000 Btu/h of total input (double), while direct communication or vertical ducts require only 1 square inch per 4,000 Btu/h.

Equation 4-1 applies to gas pressures less than 1½ psi (10.3 kPa); Equation 4-2 applies at 1½ psi and above.

Private garage appliances must be installed with a minimum 6 feet of clearance above the floor (unless protected from vehicle impact and installed per Section 305.3), while appliances in public garages and similar vehicle areas must be not less than 8 feet above the floor.

Ignition sources generally must be at least 18 inches above the floor in hazardous locations and garages, but an appliance in a separate enclosed space with access only from outside the garage is permitted at floor level provided combustion air is taken from the exterior of the garage.

Equipment supported on a level concrete slab or other approved material must extend not less than 3 inches above adjoining grade, whereas suspended equipment must be not less than 6 inches above adjoining grade.

Cast-iron pipe is explicitly prohibited for fuel gas piping systems, while wrought-iron, stainless steel and aluminum-alloy pipe are permitted under specific conditions.

The 10-minute minimum hold applies to a single-family dwelling system or a system with a volume less than 10 cubic feet; larger systems must be held 1/2 hour per 500 cubic feet of pipe volume.

On low-slope roofs with unprotected edges 6 feet or more above lower levels, a combination of warning line system and safety monitoring system is acceptable (along with guardrails, safety nets, or personal fall arrest), while guardrails with toeboards are the requirement specified for steep roofs under (b)(11).

Oxygen cylinders in storage must be separated from fuel-gas cylinders or combustible materials by a minimum of 20 feet, or alternatively by a noncombustible barrier at least 5 feet high with a fire-resistance rating of at least one-half hour.