Does a waterproof equipment box need a vacuum test?

Answer: Where a rig exists, yes: 20 kPa turns a pinhole into a readable drop within 60 seconds.

Can we sample instead of checking every unit?

Answer: Grade by risk. Seam and latch force affect opening and transit, so keep them per unit; size and wall can run five a batch.

Is ±2 mm enough on cavity length?

Answer: It depends on the liner. Foam absorbs ±2 mm; a hard EVA insert following the outline needs ±1 mm and a trial fit.

How do we judge gasket compression quickly?

Answer: Use the imprint. Close 24 hours, divide mark width by original width; 25 to 35 percent passes.

What happens to a batch that fails?

Answer: Split the causes. Oversize can be reworked; sealing and drop failures reject the batch.

Waterproof equipment box acceptance standards and test items

Quick answer: Acceptance runs in two passes. Unit by unit you check the lid seam with a feeler gauge, latch pull, wall thickness, cavity size and marking; per batch you check vacuum hold, spray and one drop. Put the thresholds on the receiving form: two inspectors must read it alike.

Where waterproof equipment box acceptance starts
Five hard checks on every unit
Measuring size and wall thickness
Sealing and vacuum on the line
Shipping documents and batch verdicts
FAQ

1. Where waterproof equipment box acceptance starts

Acceptance of a waterproof equipment box has two layers. Unit inspection reads appearance, lid seam, latches, handle and marking on every piece. Batch sampling reads vacuum hold, spray and one drop, proving this run has not drifted. Passing one says nothing about the other.

Items come from the drawing, the golden sample and the last batch record; when they disagree the sample wins. On a 520 × 290 × 190 mm box the drawing allowed ±3 mm and the sample sat within ±1 mm, so the form was set at ±2 mm, tight enough to catch mould wear.

Item	Method	Threshold
Lid seam	0.15 mm feeler gauge	Gauge does not enter
Latch pull	Pull gauge	60 to 120 N
Sealing	Vacuum, 3 per batch	Leak down 1 kPa or less

2. Five hard checks on every unit

The seam comes first. Close a waterproof equipment box and run a 0.15 mm feeler gauge round the flange; wherever it slips in, the gasket is unloaded and water enters there first.

Waterproof equipment box: a silver aluminium-frame trolley case stands on a leather workshop bench, metal corner caps, two combination latches, tools behind

Latch force is read with a pull gauge, three pulls, median recorded: under 60 N the lid opens itself on a vibration table, over 120 N a gloved hand cannot work it. A 4 mm hinge pin in a 4.05 mm bore leaves 0.3 mm of play. The handle takes 750 N for ten minutes, three times the 25 kg payload.

3. Measuring size and wall thickness

Points are fixed. On a waterproof equipment box, cavity length and width are taken 10 mm below the opening at front, middle and rear; the spread is the taper, and past 1.5 mm the liner sits tight on one side. Depth is read at four corners, smallest value rules.

Item	Instrument	Threshold
Cavity length	Tape, 1 mm scale	Range 1.5 mm or less
Wall	Ultrasonic gauge	Thinnest 2.8 mm or more
Lid flatness	Plate and feeler	1.5 mm per 300 mm

Wall thickness is read at six points: nominal 3.0 to 4.5 mm, thinnest no less than 2.8 mm, where the melt arrives last and a drop crack starts. Lid flatness past 1.5 mm over 300 mm lets the gasket middle lift, so vacuum dishes the lid instead of holding it down.

4. Sealing and vacuum on the line

Vacuum is the most reliable shop verdict. Draw 20 kPa through the valve, shut it and wait 60 seconds: a leak down of 1 kPa or less passes, and a fast drop names the side against the feeler result.

Waterproof equipment box: beige case lying on the ribbed aluminium floor of a van, two white webbing straps crossed over the lid, grey bins behind

Without a rig, spray 4 litres per minute from 300 mm for three minutes and check for wet indicator paper; that screens only. Compression is read from the imprint after 24 hours closed: 25 to 35 percent passes, and foamed silicone aged 168 hours at 70 °C must stay under 25 percent set.

5. Shipping documents and batch verdicts

Each batch of waterproof equipment box carries batch and cavity number, sampled units, raw vacuum data and the inspector's date. Cavity number is most often dropped, yet two cavities of one mould differ by 0.4 mm of wall.

The verdict doubles the sample. Three units to vacuum, all passing release; one failure doubles it to six, and six passes still release with first-round data filed; any later failure rejects the batch. Drop one unit 1.2 m onto concrete, and confirm model, batch, rating and month before release.

Situation	Action	Record
Three units pass	Release	Raw data filed
One unit fails	Sample six more	First round kept
Failure after doubling	Reject batch	Non-conformance report

Conclusion

A standard is worth only the instruments behind it: a gauge, fixed points and a threshold two inspectors read alike. Unit inspection holds appearance and assembly, batch sampling holds sealing and structure. Write the thresholds on the form, and incoming inspection of a waterproof equipment box stops depending on one person's hand.

This article discusses only the container (case body) side of specifications and design intent, and does not cover any handling, loading or use of the contents.