Most of what gets called an explosion-proof part on a forklift is an ordinary service item, and that holds for every explosion-proof forklift we build. Oil filters, air filters, fuel filters, spark plugs and timing belts are replaced on a clock, and none of them has anything to do with the Ex rating.
The parts that do carry the rating are replaced on evidence. There is no hour count for a flameproof enclosure, because the enclosure does not wear at a predictable rate. It either still holds its certified dimensions or it does not.
Schedule one: consumables, counted in engine hours
These figures are the intervals we specify for the diesel and LPG engines fitted to the counterbalance range. They assume normal duty and clean fuel. An explosion-proof forklift on double shifts in a dusty plant will need them sooner, and the air filter is usually the first to show it.
| Item | Interval | Why it is replaced on a clock |
|---|---|---|
| Engine oil and oil filter | 240-1,000 h | Changed together. The filter catches the particles that would otherwise turn the oil into sludge and block the galleries. |
| Air filter | Clean every 240-1,000 h, replace when restricted | Dust that gets past the element goes straight into the cylinders. On a forklift working in a foundry or a grain plant, the interval collapses. |
| Fuel filter | 240-1,000 h | A single-use part on both diesel and LPG engines. Water and grit in the fuel take out the injection pump long before the engine wears out. |
| Spark plug | 3,000-6,000 h | LPG and petrol engines only. A plug left in place carbonises, and the misfire shows up as lost power and higher fuel use before it shows up as a fault code. |
| Timing belt | 6,000-9,000 h | Belt-driven LPG and gas engines. Replace ahead of the interval. A belt that lets go does not stop the forklift, it destroys the head. |
The electric CPDB range has no engine, no oil circuit and no fuel system, so none of the five items above applies to it. Its service schedule covers the battery, the contactors and the braking system instead.
Schedule two: explosion-protection parts, counted in condition
Five things get checked at every service, and any one of them is grounds for replacement rather than repair.
| Part | What puts it out of service |
|---|---|
| Flameproof enclosure | Crack, deformation, or a scored joint face. The gap between the joint faces is a certified dimension, so a damaged face cannot be dressed back into tolerance. |
| Cable gland and seal | Hardened seal, a gland loosened by vibration, or a cable pulled tight around a corner. The seal is what keeps the enclosure rating intact. |
| Encapsulation | Cracked resin, exposed conductor, or a component that has overheated inside the casting. |
| Static-conductive surfaces | Coating worn through to bare metal on wheels, forks, or the chassis. An explosion-proof forklift that can hold a charge is one that can discharge it. |
| Terminal box and wiring | Loose terminal, chafed insulation, or a repair that added a joint the certificate does not cover. |
Why a damaged enclosure is replaced, not repaired
A flameproof enclosure works because of the gap between its joint faces. That gap is a dimension on the certificate, measured in tenths of a millimetre, and it is what cools the hot gas before it reaches the atmosphere outside. Grinding a score out of the face widens the gap. Welding a crack changes the material. Either repair produces an enclosure that looks sound and no longer matches the certificate it was sold under.
The same logic applies to a gland that has been overtightened, or a cable entry that has been drilled out to take a larger cable. The part is cheap relative to the forklift. The certificate it invalidates is not replaceable at all.
What a failing part looks like before it fails
Explosion-protection parts rarely fail without warning. The warnings are just easy to read as normal wear.
Surface temperature creeping up. If the same forklift on the same duty starts running hotter, something inside the enclosure is dissipating more than it used to. A loose terminal and a failing contactor look identical from the outside.
Insulation resistance falling. Measured at each service. A slow decline points to moisture ingress through a seal that has hardened, and the seal is the part to replace.
Seals that have gone hard. A seal that has lost its elasticity will pass a visual check and fail a pressure test. If it feels like plastic rather than rubber, it is done.
Bare metal where there should be coating. On wheels, forks and the chassis, the conductive coating is the static path. Worn through to bare steel, the path is broken and the charge has nowhere to go.
What to keep when a part comes off
Replacement parts for the Ex side of the forklift should arrive with their own component certificate, not just an invoice. The certificate on the forklift covers it as configured. The power unit and the instrument box are certified separately, and a replacement that does not carry the matching certificate leaves the forklift documentation incomplete even though the forklift runs.
Keep the removed part until the replacement is fitted and the paperwork matches. Buyers auditing a fleet ask for the certificate trail, and a gap in it is harder to explain than a worn part.
Regulation, briefly
In China, explosion-protected equipment in service is inspected under the special equipment rules, and the inspection covers the Ex marking and the certificate, not only the mechanical condition. Other jurisdictions put the same obligation on the site operator through their own regime. The practical consequence is the same everywhere: a part replaced with an uncertified equivalent turns a compliant forklift into a non-compliant one, and the inspection will find it.
Before ordering a replacement, check what the plate on your forklift actually declares. The marking string and what each position means is covered in how to read the nameplate, and the difference between a certificate on the forklift and one on a component is in the certification guide.
The short version
Consumables: oil and oil filter together at 240-1,000 hours, air filter cleaned on the same cycle, fuel filter on the same cycle, spark plugs at 3,000-6,000 hours, timing belt at 6,000-9,000 hours.
Explosion-protection parts: no interval. Replace on damage to an enclosure face, a gland or a seal, cracked encapsulation, worn conductive coating, or any repair that opens a certified joint.
If you are unsure which of the two a part belongs to, send us the model and the plate photograph and we will tell you what it is and where it sits on the certificate.