Heatcraft Refrigeration Products 25000102 Refrigerant Line Insulation, Refrigerant Line Support

•In systems equipped with capacity control compressors, or where multiple compressors are used with one or more compressors cycled off for capacity control, double suction risers should be installed. See Figure 6 below. The two lines should be sized so that the total cross-section area is equivalent to the cross section area of a single riser that would have both satisfactory gas velocity and acceptable pressure drop at maximum load conditions. The two lines normally are different in size, with the larger line trapped as shown. The smaller line must be sized to provide adequate velocities and acceptable pressure drop when the entire minimum load is carried in the smaller riser.

Figure 6. Double Suction Risers

•In operation, at maximum load conditions gas and entrained oil will be flowing through both risers. At minimum load conditions, the gas velocity will not be high enough to carry oil up both risers. The entrained oil will drop out of the refrigerant gas flow and accumulate in the “P”trap forming a liquid seal. This will force all of the flow up the smaller riser, there by raising the velocity and assuring oil circulation through the system.

•When connecting more than one suction line to a main trunk line, connect each branch line with an inverted trap. See Figure 7 below:

Figure 7. Inverted Trap

Installation and Operations Manual

•When brazing refrigerant lines, an inert gas should be passed through the line at low pressure to prevent scaling and oxidation inside the tubing. Dry nitrogen is preferred.

•Use long radius ell’s for lower pressure drop.

•Provide expansion loops in long straight refrigerant lines that are subject to expansion and contraction. See Expansion Loops in this manual for more information.

Refrigerant Line Insulation

•Insulate suction lines from the evaporators to the parallel unit with minimum 3/4” thickness closed-cell type insulation on low temperature circuits. Insulate suction lines on medium temperature circuits with minimum 1/2” thick insulation to prevent condensation.

•Long liquid lines run in areas exposed to high temperatures should be fully insulated with minimum 1/2” insulation.

•Suction and liquid lines should never be taped or soldered together.

Refrigerant Line Support

•Strap and support tubing to prevent excessive line vibration and noise. All tubing clamps should have an insulating material (i.e. Hydra Sorb bushing) to prevent metal to metal contact.

Figure 8. Pipe Support

•Straight runs should be supported near each end.

•Long runs require additional supports.

•A general guide is:

•3/8” to 7/8” every 5 feet

•1-1/8” to 1-3/8” every 7 feet

•1-5/8” to 2-1/8” every 10 feet

•When changing directions, supports should be placed a maximum of 2 feet in each direction.

•Piping attached to a vibrating object (such as a compressor or compressor base) must be supported in such a manner that will not restrict the movement of the vibrating object. Rigid mounting will fatigue the copper tubing.

•Use only a suitable silver solder alloy on suction and liquid lines.

•Limit the soldering paste or flux to the minimum required to prevent contamination of the solder joint internally. Flux only the male portion of the connection, never the female. After brazing, remove excess flux.

Part # 25000102