Oklahoma Natural Gas Contractor

Under the longest length method every section and branch is sized from the table row for the system's single longest run (e.g., a 12-ft branch is still sized on the 70-ft row), while under the branch length method each branch is sized using its own measured length from the meter (main length to the tee plus the branch length).

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

The code covers natural gas piping systems operating at 125 psig or less, but LP-gas piping systems only at 20 psig (140 kPa gauge) or less, except as provided in Section 402.7.

Private garages require a minimum clearance of 6 feet above the floor (unless protected from vehicle impact and installed per 305.3), while public garages, repair garages, motor fuel-dispensing facilities and other areas frequented by motor vehicles require not less than 8 feet above the floor.

The appliance itself must be 6 feet above a private garage floor, whereas the source of ignition must be elevated not less than 18 inches above the floor in hazardous locations and public, private, repair, parking garages and motor fuel-dispensing facilities.

Horizontal ducts require each opening to have not less than 1 square inch of free area per 2,000 Btu/h of total input, double the 1 square inch per 4,000 Btu/h required for vertical ducts or direct communication.

The Standard Method sets a minimum room volume of 50 cubic feet per 1,000 Btu/h of appliance input, while combining-space openings are sized at 1 square inch of free area per 1,000 Btu/h of total input but never less than 100 square inches each.

Both operate at 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 operate at nonpositive vent static pressure.

Both are Schedule 40 metallic pipe tables for natural gas at less than 2 psi inlet, but Table 402.4(1) is based on a 0.3 in. w.c. pressure drop and Table 402.4(2) on a 0.5 in. w.c. pressure drop, giving different capacities for the same size and length.

A 2A extinguisher is required for each 3,000 square feet of protected building area with travel distance not exceeding 100 feet, whereas a 10B extinguisher must be within 50 feet of wherever more than 5 gallons of flammable/combustible liquid or 5 pounds of flammable gas is in use.

Subcontractors share joint responsibility for their own portion of the work, but in no case may the prime contractor be relieved of overall responsibility for compliance for all work performed under the contract.

A written plan is normally required, but employers with 10 or fewer employees may communicate the plan orally and need not maintain a written plan.