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Pressure to the two chambers of the weld cylinder is controlled through the regulators with
associated gauges. If a Variable Pressure Option is supplied, the welder will be equipped with two pressure
regulators. One regulator is used to set the main and the other the bucking electrode force levels.
To assure that the electrode force levels are at an acceptable level before the sequence is initiated,
a control type contact gauge is supplied. This gauge only allows the sequence to be initiated when a pre-
set pressure level is reached.
If precompression end is off, the sequence starts with precompression. When this interval is
initiated, electrode force rises to the high level. When Squeeze interval is initiated the pressure then goes
to the low forge pressure. If Forge is used , it allows the electrode force to once again rise to the high level
at the beginning of a selected interval. Electrode force remains at this level until forge times out and it
drops to the lower level, or if hold is initiated, it will remain at the high level. In Variable Pressure, electrode
force rises to the high level at the beginning of hold.
Variable Pressure machines can also be used in the Constant Low and Constant High modes. In
these two latter modes, only one level of electrode force is obtained. The main difference between these
modes is that in Constant Low electrode force is the result of the main and bucking pressures. In Constant
High, electrode force is the result of only the main, high pressure setting.
CONSTANT PRESSURE ONLY AND SEQUENCE
Constant Pressure only machines are equipped with a pressure gauge in addition to a contact gauge.
The pressure gauge monitors pressure in the lower chamber of the weld cylinder. A sequence is only
initiated when the contact gauge and pressure switch are closed: Upper chamber pressurized, Lower
chamber exhausted.
ELECTRODE FORCE CHARGE
Cyl. Cyl. PRESSURE—PSI GUAGE
Dia. Area 30 40 50 60 70 80
2”
3.14 95
125 157 188 220 250
2 ½” 4.91 147 196 246 294 344 392
3” 7.07 212 283 354 424 495 565
3 ½” 9.62 288 385 481 576 675 770
4” 12.57 377 500 629 754 878 1000
4 ½” 15.90 477 635 795 954 1115 1270
5” 19.64 590 735 982 1180 1375 1570
6” 28.27 848 1130 1414 1696 1978 2260
8” 50.27 1515 2010 2514 3030 3525 4020