The WZPK-22I-C is a threaded stainless steel temperature sensor built around a PT100 platinum resistance element. A 160 mm probe carries the element into the pipe or vessel, the threaded body holds it against pressure and flow, and the sealed connection head takes the wiring out through a waterproof port. There is no dial and no local readout on this one: the element returns a resistance value, and the indicator, transmitter or PLC at the far end of the cable turns that into a temperature.
The format suits lines where nobody wants to stand and squint at a gauge — engine-room cooling and lubricating circuits, boiler feed and condensate, chilled and hot water in plant rooms, gas ducts downstream of a blower. The probe is stainless steel throughout, which is why it is chosen for water, coolant and mildly aggressive process fluids where a plated or mild-steel probe would pit within a season.
Mechanically it is the familiar pattern: sealed head, hex body, thread into the fitting, cap tethered on a short chain. If the part coming out of your line is catalogued as an explosion-proof thermocouple temperature sensor, this unit will look and fit the same way. The element inside, though, is a PT100 RTD rather than a thermocouple junction, so the input type at your instrument is the one thing worth checking before the order goes in.
The standard build is a 160 mm probe with a 0–200 °C span. Other lengths, threads, spans and wiring arrangements are built to order; the label on the old head and a photo of the thread are usually enough for us to match it.
| Product Name | Temperature Sensor |
| Model | WZPK-22I-C |
| Sensing Element | PT100 platinum resistance (RTD) |
| Probe Length | L: 160 mm |
| Material | Stainless Steel |
| Accuracy Class | ±0.5%FS |
| Temperature Range | 0-200°C |
| Process Connection | Threaded interface (thread matched to your port) |
| Head | Sealed connection head with waterproof wiring port and sealing ring |
| Features | Corrosion resistance, high temperature resistance, high measurement accuracy, stable performance. |
| Application | Used for liquid temperature, gas temperature and other temperature measurement |
| Customized Services | Yes |
Inside the sheath sits a PT100 platinum resistor. Platinum resistance rises with temperature in a well-characterised curve — 100 Ω at 0 °C — and the instrument measures that resistance, compares it with the curve and displays degrees. Because the element is a resistor, the voltage the instrument sees also depends on the resistance of the cable, so the wiring arrangement matters: two wires are usually fine on a short run, while a three- or four-wire connection cancels lead resistance and is the better choice on long cable runs or where the low end of the range has to stay accurate.
A thermocouple works the other way round. Two dissimilar conductors joined at a hot junction generate a small voltage — the Seebeck effect — and the instrument reads that voltage and compensates for the temperature at the cold end, where the leads meet the terminals. The junction itself has to be soundly welded and insulated from its sheath to avoid short circuits and false readings. That cold-junction compensation is why a thermocouple loop is wired differently from a resistance loop, and why the two types are not interchangeable on the same input card. This model is the resistance type, so a thermocouple input needs a transmitter or a different card between the probe and the panel.
For day-to-day use the numbers are easy to work with. The ±0.5%FS accuracy class over the full 0–200 °C span works out to roughly ±1 °C across the range, which is comfortable for cooling water, lube oil, feedwater and duct air. The sheath protects the element, and a heavier wall buys mechanical strength at the cost of a slightly slower response — worth knowing if the probe sits in a small, fast-moving line.
Physically it is the same fitting you would use for a liquid and gas temperature measurement thermocouple — same thread, same head, same insertion depth — with a resistance element inside and a resistance input at the panel.
| Document | What it covers |
| Dimensional drawing | Probe length, thread, head outline and insertion depth for the unit being supplied |
| Wiring diagram | Terminal arrangement for the element and the connection your instrument expects |
| Material statement | Probe and head alloy, for your medium and your own inspection sheet |
| Element check record | Resistance reading at ambient, taken before the unit is dispatched |
| Packing and labelling detail | How the units are boxed and marked if your store needs its own labels or kits |
| Custom build drawing | The agreed length, thread, range and wiring, issued for your approval before machining |
What the name describes. The catalogue title calls this an explosion-proof thermocouple temperature sensor, and the hardware follows that pattern: a machined hex body, a threaded stem that seats into the boss, and a capped head with a glanded cable entry. That describes how the unit is built. It is not a statement that a notified body has assessed it.
Where the sealing stops. The waterproof ring and cable gland keep splash, washdown water and damp engine-room air away from the terminals. They do not form a flameproof enclosure, and the head alone does not make a loop safe to open in a flammable atmosphere — isolation and permit-to-work rules still apply.
Documents that travel with the unit. Each order can be accompanied by a material statement covering the probe and head, an ambient resistance check record for the element, a dimensional drawing showing insertion depth and thread, a terminal wiring diagram, and packing and labelling detail if your store needs its own marks on the cartons.
Documents that are not standard. No ATEX, IECEx or classification-society certificate is issued with the standard build, and we will not describe the unit as approved for a classified area without one in hand. If your project specification requires that paperwork, raise it when you ask for the quotation — not after the probe has been machined.
What to send with an enquiry for a classified position. The zone or division, the gas group and temperature class, the medium and working pressure, and the exact document your surveyor or inspector expects to see. With those four we can give you a straight answer before you commit rather than after the unit is on the bench.
Replacing an existing certified unit. Swapping a certified probe for an uncertified one changes the status of that measurement point, and different surveyors treat it differently. Confirm with the attending surveyor or your technical superintendent before the old unit comes out: the thread and insertion depth will match, the paperwork position may not.
Custom builds and paperwork together. Length, thread, range and wiring are agreed on a drawing you approve before machining, and the document pack is fixed at the same time, so the approval question is settled while the probe is still a drawing rather than after it is boxed and on its way to the vessel.
Buying instrumentation for a vessel or a plant usually comes down to matching the part to the job. Our team at Jiangmen Jiexi Machinery Equipment Co., Ltd. has worked with buyers worldwide since 2013, and we start before the order: confirming the range, thread, connection and mounting you need, checking a model or part number against the equipment on site, and saying plainly where a standard unit stops and custom work begins. After delivery we stay reachable for installation, commissioning and fault-finding, with quality control that includes two extra testing steps beyond industry standard.
The head is sealed against water and dust and the assembly is built for wet, dirty engine-room and plant conditions, but that is a construction statement rather than an approval. The model is catalogued in the same head-and-thread format as an explosion-proof thermocouple temperature sensor, so it will physically replace one; whether the installation is acceptable depends on the area classification and the document your inspector asks to see. Tell us the classification and what your surveyor expects, and we will confirm what can actually be supplied for that position.
The probe and head are stainless steel and the wetted parts are chosen for water, coolant, condensate and most plant fluids. For seawater, chlorinated water, dilute acids or a gas stream that runs wet, tell us the medium and the concentration before the order is placed — the right answer may be a different alloy or a heavier sheath, and that decision has to be made before the probe is built. In this liquid and gas temperature measurement thermocouple layout the tip sits directly in the medium, so the alloy is doing the work; there is no coating to rely on.
Yes. The 160 mm PT100 version is the standard build, and as a custom temperature sensor manufacturer we build to a drawing: a longer sheath for a deep tank or a wide duct, a thread to match a non-standard boss, a span inside or outside the 0–200 °C band, or a different wiring arrangement for your panel. Send the port thread, the insertion depth you need and the medium, and we will issue a drawing for approval before anything is machined.
Not directly. A PT100 is read as a resistance, while a thermocouple input expects a microvolt signal with cold-junction compensation, and the two do not share a card. You can keep the probe and put a resistance-to-current transmitter between it and the panel, or tell us what the input card is and we will say whether a thermocouple version can be built in the same head-and-thread body.
It is the length of the probe that goes into the line, and the drawing we issue for the build shows the dimension from the seating face to the tip so you can check it against your tapping. Boss height, insulation thickness and pipe wall all change how much of the sheath reaches the flow, so it is worth offering the old probe up against the drawing before the unit is made.
