Honeywell Sensepoint XCD SPXCDULNFX – Fixed LEL Detector (0-100%LEL, Catalytic bead (poison-resistant), UL, LM25, 3/4" NPT)
SPXCDULNFX is the catalytic-bead LEL transmitter on Sensepoint XCD, 0–100 %LEL default, LM25 epoxy-coated aluminium, 2 × 3/4" NPT, UL / CSA. Choose it for general hydrocarbons where infrared windows would fog or the budget cannot justify dual-beam IR.
Same gas, swap enclosure/approval: aluminium SPXCDALMFX, 316SS SPXCDASMFX, UL SPXCDULNFX. SPXCDALMFX · SPXCDASMFX · SPXCDULNFX
Part-number decode
| Segment | Meaning | This SKU |
|---|---|---|
| SPXCD | Sensepoint XCD series | SPXCD |
| A / U | Approval A=ATEX/IECEx/GB; U=UL | U |
| L / S | Enclosure L=LM25 aluminium; S=316SS | L |
| M / N | Entry M=M20; N=3/4" NPT | N |
| FX | Gas flammable gas (catalytic), Catalytic bead (poison-resistant) | FX |
Same gas, swap enclosure/approval: aluminium SPXCDALMFX, 316SS SPXCDASMFX, UL SPXCDULNFX.
Technical specifications
| Target gas | LEL / flammable gas (catalytic) |
|---|---|
| Principle | Catalytic bead (poison-resistant) |
| Default range | 0-100%LEL |
| User FSD window | 20-100%LEL |
| Resolution | 10%LEL |
| Output | 4–20 mA sink/source + optional Modbus RTU |
| Supply | 16–32 VDC (24 VDC nominal) |
| Power | 4.9 W |
| Enclosure | LM25 epoxy-coated aluminium |
| Entries | 2 × 3/4" NPT |
| Display | Tri-colour backlight LCD |
| Relays | 3×5A@250VAC |
| Ingress | IP66 |
| Approvals | UL / CSA |
| Temperature | −40~+65 ℃ |
| Mass | approx. 2.0 kg (4.4 lb) |
Why this principle for this gas
A poison-resistant pellistor sees the heat of combustion and therefore works on a wide hydrocarbon mix, including species IR filters miss. It is not a toxic detector. Mount above potential release points for gases lighter than air and below for heavier vapours; keep silicone sealants and leaded petrol away from the sinter.
Sensor and replaceable parts
OEM cartridge SPXCDXSFXSS. Calibration cap S3KCAL. Collecting cone follows buoyancy—see installation. Pipe/duct kits: SPXCDMTBR / SPXCDDMK.
Typical applications
Pump rooms, filling gantries and compressor packages still standardise on catalytic LEL because the gas slate is mixed. XCD locks the 4–20 mA into the ESD matrix and allows magnetic bump test without a hot-work permit to open the lid.
Selection contrast
| P/N | Gas | Range | Principle |
|---|---|---|---|
| SPXCDULNFX | LEL | 0-100%LEL | Catalytic bead |
| SPXCDULNRX | CH₄ | 0-100%LEL | IR |
| SPXCDULNPX | C₃H₈ | 0-100%LEL | IR |
| SPXCDULNHX | H₂S | 0-50ppm | EChem |
| SPXCDALMFX | LEL | 0-100%LEL | Catalytic bead |
| SPXCDASMFX | LEL | 0-100%LEL | Catalytic bead |
Installation and wiring
Wall-mount SPXCDULNFX (flammable gas (catalytic), LM25 epoxy-coated aluminium) through the one-piece plate with M8 bolts sized for that mass. This SKU uses 2 × 3/4" NPT entries: pipe kit SPXCDMTBR covers Ø1.5–3″, duct kit is SPXCDDMK, and glands must match—do not retap SPXCDULNFX. Land SPXCDULNFX 4–20 mA as three-wire and set Modbus address from the menu only. Magnetic wand calibration on the SPXCDULNFX lid stays non-intrusive. Keep silicones off the SPXCDULNFX pellistor; light hydrocarbons high, heavy vapours low.
FAQ
- SPXCDULNFX: Will silicone vapours kill this LEL bead?
- SPXCDULNFX — Yes, silicones and chlorinated solvents poison pellistors. Specify the IR methane or propane SKU if those contaminants are routine.
- SPXCDULNFX: What bump-test gas should I use?
- SPXCDULNFX — Use the target hydrocarbon at 50 %LEL. Methane-only test gas will under-state response if the process is petrol vapour.
- LM25 or 316SS for SPXCDULNFX (flammable gas (catalytic))?
- SPXCDULNFX ships in LM25 epoxy aluminium (~4.4 lb). For flammable gas (catalytic) in salt spray, caustic CIP or sour-water splash, switch to 316SS sibling SPXCDASMFX instead of painting this lid.
- Why is SPXCDULNFX NPT instead of M20?
- SPXCDULNFX is the UL/CSA flammable gas (catalytic) body and ships 3/4" NPT. Do not tap M20 on this lid—order ATEX sibling SPXCDALMFX if metric glands are mandatory.
- Can I retrofit Modbus on SPXCDULNFX after it ships?
- Modbus RTU on SPXCDULNFX is a transmitter sales option, not a jumper on the flammable gas (catalytic) lid. Confirm the option before the box leaves; 4–20 mA sink/source is already on this SKU.
Documents
Honeywell Sensepoint XCD datasheet / manual · On-site XCD selection matrix
Availability and enquiry
Stock is lot-based. If this aluminium ATEX box is out, jump to 316SS SPXCDASMFX or UL SPXCDULNFX rather than a dead SKU.