PT-36 Mechanized Plasmarc Cutting Torch Instruction Manual

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section 4operation4.3 Torch Flow Passagesplasma gas inshield gas inwater inwater outView showing gas passages152View showing water passages
section 5Maintenance5.1 IntroductionWear on torch parts is a normal occurrence to plasma cutting. Starting a plasma arc is an erosive process to boththe electrode and nozzle. Regularly scheduled inspection and replacement of PT-36 parts must take place tomaintain cut quality and consistent part size.DANGERHydrogen explosion hazard.A hazard exists whenever a water table is used for plasma arc cutting operations withoutfollowing recommended practices for safe operation. Severe explosions have resultedfrom the accumulation of hydrogen beneath the plate being cut. Thousands of dollarsin property damage has been caused by these explosions. Personal injury or death couldresult if people are struck by flying debris from the explosion.The best available information indicates three possible sources of hydrogen in water tables.Most of the hydrogen is liberated by a fast reaction of molten metal from the kerfwith the water to form metallic oxides. This reaction explains why reactive metals with agreat affinity for oxygen, such as aluminum and magnesium, release greater volumes ofhydrogen during the cut than iron does. Most of this hydrogen will come immediately tothe surface, but some of it will cling to small metallic particles. These particles will settle tothe bottom of the water table and the hydrogen will gradually bubble to the surface.Hydrogen may also result from slower chemical reactions of cold metal particles with thewater, dissimilar metals, or chemicals in the water table. This hydrogen will also graduallybubble to the surface.Finally, hydrogen may come from the plasma gas if H-35 is used. This gas is 35 percenthydrogen by volume and a total of about 70 cfh of hydrogen will be released.The hydrogen gas can collect in several places. The most common is in pockets formed bythe plates being cut and slats on the table. Pockets may also be formed in warped plates.There can also be an accumulation of hydrogen under the slag tray or even in the air reservoir.This hydrogen, in the presence of oxygen, can then be ignited by the plasma arc or aspark from any source. To reduce chances of hydrogen generation and accumulation, anda consequent explosion, the following practices are recommended:1. Clean the refuse (particularly fine particles) from the bottom of the table frequently.Refill the table with clean water.2. Do not leave plates on the cutting table overnight or over weekends.3. If water tables have been sitting idle for several hours, vibrate the table in some waybefore the first plate is laid in position. This will allow accumulated hydrogen in therefuse to break loose and dissipate before it is confined by a plate on the table. Thismight be accomplished by laying the first plate onto the table with a slight jolt, thenraising it again to permit hydrogen to escape before it is finally positioned.4. If cutting above water, install fans to circulate air between the plate and the water.5. If cutting under water, agitate the water under the plate to prevent accumulations ofhydrogen. This can be done by aerating the water using compressed air.6. The level in the water table can be raised and lowered between cuts to dissipate accumulatedhydrogen.7. Maintain pH level of the water near 7 (neutral). This should reduce the rate of chemicalreaction between water and metals.153
Page 2 and 3: Be sure this information reaches th
Page 4 and 5: table of contents134
Page 6 and 7: section 1safety precautionsWARNINGW
Page 8 and 9: section 2DEscription2.4 Optional Ac
Page 10 and 11: section 2DEscriptionPT-36 600A Star
Page 12 and 13: section 2DEscription142
Page 14 and 15: section 3INstallation3.1.2 Connecti
Page 16 and 17: section 4operationWARNINGExplosion
Page 18 and 19: section 4operationcautionBefore att
Page 20 and 21: section 4operation4.2.4. Surface Fi
Page 24 and 25: section 5Maintenance5.2 Torch Front
Page 26 and 27: section 5Maintenance7. Remove elect
Page 28 and 29: section 5Maintenance4. Unscrew nozz
Page 30 and 31: section 5Maintenance5.4 Assembly Of
Page 32 and 33: section 5Maintenance3. Screw electr
Page 34 and 35: section 5Maintenance5.7 Removal and
Page 36 and 37: section 5Maintenance4. To install t
Page 38 and 39: section 5MaintenanceChecking for Co
Page 40 and 41: section 5Problem: Failure to startS
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PT-36 Mechanized Plasmarc Cutting Torch Instruction Manual

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