(4), motor (7), multibreaker (l), power cable (9), and base (8). The only difference between the models lies in the type of compressor supplied; however, the compressors are interchangeable between the models. A spare parts kit, recharging transfer fittings, and charging fittings are used in conjunction with the units.
The repulsion start induction single-phase motor, shown in figure 3-3, is a 115- to 230-volt, 60-cycle, three-fourths horsepower unit. It operates at 1750 rpm and draws 9.8 amperes at 115 volts. This type of motor supplies very high starting torque with a very low starting current. In starting, the motor has repulsion motor characteristics; but at running speeds, it functions as an induction motor since the motor windings are automatically short-circuited and the brushes are lifted from the commutator when the operating speed is approached.
The thermal, magnetic multibreaker, shown in figure 3-3, is a two-pole, 115-volt ac, 20-ampere unit installed to protect the power circuit from overloads. In addition, it acts as a manual ON/OFF switch for the operation of the transfer unit. If the multibreaker trips because of a power overload, you may reset it by placing the switch first to OFF and then to ON.
This unit, shown in figure 3-4, is a two-stage, single-action, displacement-type compressor. The running gear assembly actuates the unit and transfers the liquid carbon dioxide from the supply cylinder to the cylinder being recharged. The lower section consists of a cylinder body (6), plunger (7), molded metallic packing (8), spacer (10), and plunger guide (9). The plunger (7), which acts as a piston and transfers the liquid carbon dioxide, is connected to the crosshead of the running gear assembly. The upper section of the unit consists of a cylinder head (2) with an intake and outlet port, an intake valve (11), a discharge valve disc (4), and a discharge valve cap (l). A safety disc and washer, located in the cylinder head behind the safety disc plug (13), releases the carbon dioxide from the compressor when the pressure exceeds the 2650- to 3000-psi range.
Figure 3-4. - Compressor Assembly, Model 4211 Carbon Dioxide Transfer Unit.Continue Reading