Plasma Air-Supply Diagnostics

This annex is for one of the highest-frequency false diagnoses in the library: blaming the plasma cutter when the real problem is air quality, inlet pressure, or air delivery under flow.

Use it with plasma guides in this library from:

Hypertherm
Thermal Dynamics
Miller plasma
Everlast
PrimeWeld
YesWelder
Forney
Eastwood
Harbor Freight

Core rule

Static regulator pressure is not enough. Diagnose plasma air under flow.

Air-diagnostic ladder

1. Verify air quality

drain water separators
inspect filter condition
confirm the air is dry and free of oil

2. Verify pressure under flow

do not trust a static reading only
reproduce the complaint while watching usable pressure
identify pressure collapse that appears only during the cut attempt

3. Verify delivery path

inspect hose restrictions and couplers
inspect inlet fittings for leaks
confirm the machine is seeing adequate inlet supply at the torch duty being attempted

4. Verify the rest of the external path

move the work clamp to bright clean metal
replace worn nozzle and electrode or cartridge
retest on clean mild steel with conservative travel speed

Symptom matrix

Symptom	Most likely air-side branch	High-value first test
No pilot or no start	inadequate pressure under flow, clamp, torch cap or cartridge seating	verify flow pressure, clamp, and front-end setup
Pilot okay, poor transfer	clamp or coated workpiece, borderline air delivery	move clamp and verify airflow under load
Poor cut quality	wet air, worn consumables, too much speed	replace parts and retest with dry air
Short consumable life	wet air, oily air, poor pierce technique	correct air quality and technique before escalation
Intermittent faults after several minutes	compressor capacity, heat in hose path, pressure collapse	reproduce hot and watch air performance under flow

Brand and family notes

Hypertherm XP and AIR

Separate built-in-air compressor behavior from torch behavior on AIR units.
On XP models, cap and consumable stack order stay important alongside air quality.

Hypertherm SYNC

Air, clamp, and cartridge recognition form one chain.
Do not interpret a SYNC readiness complaint without first proving dry air under flow.

Thermal Dynamics Cutmaster

Torch lead and air path are the first branches on intermittent start complaints.
If a symptom follows one torch assembly, stop broadening the diagnosis.

Everlast, PrimeWeld, YesWelder, Eastwood, Harbor Freight, Forney

On these prosumer and budget platforms, wet air and marginal compressor output account for a disproportionate share of "bad machine" complaints.
Keep the first branch in filtration, pressure drop, clamp quality, and consumables.

Technician checklist

Reproduce the complaint with known-good dry air.
Watch pressure under flow.
Replace or confirm front-end consumables.
Move the clamp.
Retest on clean mild steel at moderate speed.

If the complaint disappears, stop there.

Escalate sooner when

the machine still will not start with known-good dry air, clamp, and consumables
the same fault repeats from a cold start with proven air delivery
there is internal leakage, electrical smell, or clearly abnormal thermal behavior

Source posture

This annex is synthesized from the plasma guides in this repository.
Exact inlet pressure ranges and consumable limits should still be taken from the affected machine's manual.