Honeywell Sensepoint XCD SPXCDULNNX – Fixed NO₂ Detector (0-50ppm, Electrochemical (Surecell™), UL, LM25, 3/4" NPT)
SPXCDULNNX is the Sensepoint XCD nitrogen dioxide electrochemical transmitter, 0–50 ppm default, LM25 epoxy-coated aluminium, 2 × 3/4" NPT, UL / CSA. It is aimed at diesel halls, tunnel plant rooms and nitric-acid fill points.
Same gas, swap enclosure/approval: aluminium SPXCDALMNX, 316SS SPXCDASNNX, UL SPXCDULNNX. SPXCDALMNX · SPXCDASNNX · SPXCDULNNX
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 |
| NX | Gas nitrogen dioxide, Electrochemical (Surecell™) | NX |
Same gas, swap enclosure/approval: aluminium SPXCDALMNX, 316SS SPXCDASNNX, UL SPXCDULNNX.
Technical specifications
| Target gas | NO₂ / nitrogen dioxide |
|---|---|
| Principle | Electrochemical (Surecell™) |
| Default range | 0-50ppm |
| User FSD window | 10-50ppm |
| Resolution | 5ppm |
| Output | 4–20 mA sink/source + optional Modbus RTU |
| Supply | 16–32 VDC (24 VDC nominal) |
| Power | 3.7 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
NO₂ is heavier than air and rides exhaust plumes toward floor trenches. Surecell™ electrochemistry is required; IR and catalytic channels do not quantify NO₂. Mount low on the exhaust side of the engine hall, not on the fresh-air intake.
Sensor and replaceable parts
OEM cartridge SPXCDXSN1SS. Calibration cap S3KCAL. Collecting cone follows buoyancy—see installation. Pipe/duct kits: SPXCDMTBR / SPXCDDMK.
Typical applications
Standby-generator rooms, road-tunnel niches and fertiliser fill bays need a dedicated NO₂ point tied to extract fans. XCD holds that interlock; a badge dosimeter only explains the exposure after the fact.
Selection contrast
| P/N | Gas | Range | Principle |
|---|---|---|---|
| SPXCDULNNX | NO₂ | 0-50ppm | EChem |
| SPXCDULNCX | CO | 0-300ppm | EChem |
| SPXCDULNHX | H₂S | 0-50ppm | EChem |
| SPXCDULNO1 | O₂ | 0-25.0%Vol | EChem |
| SPXCDALMNX | NO₂ | 0-50ppm | EChem |
| SPXCDASNNX | NO₂ | 0-50ppm | EChem |
Installation and wiring
Wall-mount SPXCDULNNX (nitrogen dioxide, 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 SPXCDULNNX. Land SPXCDULNNX 4–20 mA as three-wire and set Modbus address from the menu only. Magnetic wand calibration on the SPXCDULNNX lid stays non-intrusive. SPXCDULNNX NO₂ sits low on the exhaust wall.
FAQ
- SPXCDULNNX: Does the NX cell also read NO?
- SPXCDULNNX — It is specified for NO₂. If you have nitric oxide you need a different cartridge family—do not assume NX covers both.
- SPXCDULNNX: What FSD options exist?
- SPXCDULNNX — Default 0–50 ppm, user window 10–50 ppm in 5 ppm steps. Tunnel niches usually stay at 20 ppm FSD.
- LM25 or 316SS for SPXCDULNNX (nitrogen dioxide)?
- SPXCDULNNX ships in LM25 epoxy aluminium (~4.4 lb). For nitrogen dioxide in salt spray, caustic CIP or sour-water splash, switch to 316SS sibling SPXCDASNNX instead of painting this lid.
- Why is SPXCDULNNX NPT instead of M20?
- SPXCDULNNX is the UL/CSA nitrogen dioxide body and ships 3/4" NPT. Do not tap M20 on this lid—order ATEX sibling SPXCDALMNX if metric glands are mandatory.
- Can I retrofit Modbus on SPXCDULNNX after it ships?
- Modbus RTU on SPXCDULNNX is a transmitter sales option, not a jumper on the nitrogen dioxide 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 SPXCDASNNX or UL SPXCDULNNX rather than a dead SKU.