Does a waterproof chemical case need full immersion testing?

Answer: Not on routine batches. Immersion belongs to the type test; production runs use a 20 kPa hold plus a 24-hour fill. A soaked case cannot be re-used.

What gasket hardness should the standard call for?

Answer: 70 Shore A for EPDM, 75 for nitrile. Under 65 the cord extrudes from the groove; over 80 the latch force is more than a thin wall carries.

Can offcuts be used as soak coupons?

Answer: Yes, if they share compound, cavity and wall thickness. Offcuts have been heated twice, so results read high.

One unit in two hundred leaks. What next?

Answer: Move to tightened inspection with a doubled sample. If that lot still fails, reject the batch and audit grooves and gasket lot together.

How often is the type test repeated?

Answer: Every six months, and at once on any change of compound, mould or gasket.

Waterproof Chemical Case Acceptance Standards: Tests and Limits

Quick answer: A waterproof chemical case is accepted in four layers: incoming, first-off, patrol and type test. Density of 0.945 to 0.960 g/cm³, compression of 22% to 28% and a 1.5 kPa drop at 20 kPa are the limits to measure first.

How Acceptance Checks for a Waterproof Chemical Case Are Layered
Verifying Resin and Chemical Resistance
Seal Geometry and Air-Holding Tests
Drop, Stacking and Salt Spray Judgments
Sampling Plans and Batch Decisions
FAQ

1. How Acceptance Checks for a Waterproof Chemical Case Are Layered

Disputes over a waterproof chemical case rarely concern whether water entered, only who owns the leak, so the standard cuts responsibility at the process step.

The type layer is usually empty: the order names an immersion grade and nothing records media compatibility. Its samples are destructive, so they are built apart.

Layer	Object	Criterion	Frequency
Incoming	HDPE, gaskets	0.945 to 0.960 g/cm³, 70 Shore A	Every batch
First-off	First shot per mould	Wall, groove, latch force	Mould change
Patrol	Running output	Appearance, 20 kPa hold	5 units per 2 hours
Type test	Complete case	Soak, drop, stack, spray	6 months

2. Verifying Resin and Chemical Resistance

Resin first, wall second. The body is high-density polyethylene held between 0.945 and 0.960 g/cm³, with walls at 3.0 to 4.5 mm; ultrasonic gauging fails below 2.8 mm.

Waterproof chemical case: an olive-green case on a scarred bench, a wide latch over the parting line, a round valve at right, blurred scope behind

Media resistance needs a soak rather than a datasheet. Coupons from the same cavity sit at 40 °C for 72 hours and must show mass change within 3%; the assembled waterproof chemical case then takes a 24-hour internal fill.

Media	Concentration	Condition	Limit
Sulphuric acid	30%	40 °C, 72 h	Mass change ≤ 3%
Sodium hydroxide	40%	40 °C, 72 h	Shift ≤ 5 Shore A

The gasket fails before the body does: nitrile suits oil, EPDM covers acids, and fluoroelastomer resists solvents at four times the cost.

3. Seal Geometry and Air-Holding Tests

Groove geometry sets compression. A groove 8.0 mm wide and 5.0 mm deep for a 6.0 mm cord lands at 22% to 28% when the lid closes; past 30% the cord takes a permanent set.

Air holding is judged on positive pressure: charge to 20 kPa, stabilise 30 seconds, then allow a 1.5 kPa drop in 60 seconds. Negative pressure does not convert, so the report must name it.

The valve is the item inspectors skip: it opens at 8 kPa differential, and the back-flow check is to fill the case, stand it two hours and look for water.

4. Drop, Stacking and Salt Spray Judgments

Mechanical tests on a waterproof chemical case run least to most destructive, so stacking precedes drop. The sample spends four hours at minus 18 °C, then takes six faces, three edges and one corner from 1.2 m.

Waterproof chemical case: a long black case open on the floor, four lid latches, foam in the lid, a rifle in cut foam, front handle

Stacking puts three tiers up with 180 kg on the top lid for 48 hours, with height change inside 2 mm.

Test	Condition	Limit
Drop	−18 °C, 1.2 m, six faces	No through-crack
Stacking	3 tiers, 180 kg, 48 h	Change ≤ 2 mm
Salt spray	Neutral, 48 h	No red rust

5. Sampling Plans and Batch Decisions

For a waterproof chemical case, sampling follows an adjusting attribute plan at general level II. Appearance carries an AQL of 2.5 and function 0.65, judged apart, and exceeding Ac on either rejects the batch.

Lot size	Sample	Appearance Ac / Re	Function Ac / Re
151 to 280	32	2 / 3	0 / 1
281 to 500	50	3 / 4	0 / 1

Every sample carries a number linked to machine, cavity and shift, kept three years. Solvent service needs surface resistance of 10 to the 6th to 10 to the 9th ohm, and labels must survive 50 solvent rubs.

Conclusion

An acceptance standard is not a filter for rejecting suppliers; it turns each judgment into a repeatable action. Tie the four layers into one chain and batch variation stays inside a band you can defend, which is what a waterproof chemical case standard should deliver.

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.