The PURE Humidifier SX Series is a steam-to-steam heat exchanger humidifier that converts boiler steam into clean humidification steam, with a capacity up to 2,035 lbs/hr, made by PURE Humidifier Co. of Chaska, Minnesota — a commercial and industrial humidification manufacturer, not to be confused with Pure Enrichment, the consumer humidifier brand. This guide covers how to identify your SX unit and which parts we stock are commonly used on it.
What the SX Series is and where it's used
The SX Series is rated up to 2,035 lbs/hr. Like the rest of the PURE line, it uses SCR (silicon-controlled rectifier) modulation to hold humidity within about ±1–2% RH, and disperses steam through straight injection tubes or PURE's Fast-Pac or Insty-Pac dispersion assemblies. Instead of a heating element or burner, it uses a rectangular tube heat exchanger to turn existing boiler steam into fresh, chemical- and mineral-free humidification steam.
SX vs. SXDDR: how to tell which one you have
Check the model string on the nameplate: if it ends in “DDR,” you have the deionized/demineralized (or reverse-osmosis) water version. If not, you have the standard-water base model.
Base-model SX units use Tri-Probe electrode water-level control and a motorized brass drain valve, plus an adjustable surface water flusher. SXDDR units run on DI/RO water instead, using a stainless float-operated fill valve, a stainless float-operated low-water cutoff, a stainless overflow standpipe, and a stainless manual ball-valve drain in place of the Tri-Probe electrodes and motorized drain valve. The two variants don't share water-level or drain parts — check your nameplate before ordering.
How to tell it apart from PURE's other series
- ES Series: the ES heats water electrically to make steam, rather than exchanging heat from boiler steam.
- EC Series: the EC is a compact, cabinet-style electric unit built for wall mounting.
- ER Series: the ER is a small-capacity electric unit for environmental rooms and chambers, up to 21 lbs/hr.
- GX Series: the GX is gas-fired (natural gas or propane) rather than steam-to-steam.
Replacement parts we stock for the SX Series
The parts below are commonly used on the SX Series based on PURE's published documentation. Confirm against your unit's nameplate and O&M parts list before ordering — PURE has made design changes across production runs.
Base-model (SX) parts
- 05328 — ES/SX/GX Tri-Probe Assembly — Tri-Probe electrode water-level control (also used on base ES and GX units).
- 05383 — Size 1 Side Entry Gasket 8x11 — Size 1 side-entry gasket — confirm your unit's size.
- 05384 — Size 2 Side Entry Gasket 8x19 — Size 2 side-entry gasket — confirm your unit's size.
- 05385 — Size 3 Side Entry Gasket 8x27 — Size 3 side-entry gasket — confirm your unit's size.
- 05386 — Size 4 Side Entry Gasket 8x47.25 — Size 4 side-entry gasket — confirm your unit's size.
- 15166 — Tri-Probe O-Ring — O-ring for the Tri-Probe electrode assembly.
- 15164 — Flusher O-Ring — O-ring for the surface water flusher.
- 09142 — Normally Closed Drain Valve Z2075Q-K + CQKB24-RR — motorized brass drain valve, normally closed.
- 09143 — Normally Open Drain Valve Z2075Q-K + CQKB24-LL — motorized brass drain valve, normally open.
DDR-model (SXDDR) parts
- 09079 — DDR Float Ball & Arm Assembly, Small — float ball & arm (small) for the DDR fill valve.
- 09030 — DDR Float Ball & Arm Assembly, Big Orifice — float ball & arm (big orifice) for the DDR fill valve.
- 05052 — DDR Water Inlet / Float Plate Gasket — gasket for the DDR water inlet / float plate.
- 09128 — KIP 1/4" SST Fill Valve 2X2599-24/50-60 — stainless float-operated fill valve.
- 15048 — Liquid Level Switch, Vertical, 1/4" (9871-09490) — float-operated low-water cutoff switch.
Control, safety and maintenance items used across the PURE line
Not specific to one series — commonly used across PURE's ES, EC, ER, GX and SX units.
- 15047 — Over Temp Switch SE-L250M — over-temperature safety cutoff switch.
- 12354 — SCR Relay, Crydom HD6050TH S1 — SCR modulation relay.
- 15184 — #12 Zinc SAE Washer (FW#12Z) — hardware washer.
- 16300 — PUREClean Descaler, 45 lb — descaling treatment for periodic maintenance.
Where to find the official parts list and manual
We haven't reproduced PURE's numbered parts diagrams here. For the definitive parts list, use the factory O&M manual, which contains the numbered parts list and diagram for your unit:
Before you order
Confirm your unit's exact model and serial number from its nameplate before ordering — base and DDR models don't share water-level or drain parts. See our guide to OEM vs. aftermarket HVAC parts, browse everything we stock in our PURE Humidifier replacement parts collection, or contact us with your model and serial number and we'll help confirm fit.
Frequently Asked Questions
Is an SXDDR part interchangeable with an SX part?
No. The SXDDR uses DI/RO-water components — a stainless float-operated fill valve, float-operated low-water cutoff, and manual ball-valve drain — while the base SX uses Tri-Probe electrode water-level control and a motorized brass drain valve. Confirm from your nameplate before ordering.
Which PURE series is sized for small loads like environmental rooms or chambers?
The ER Series is PURE's smallest-capacity unit, built for environmental rooms and chambers up to 21 lbs/hr.
Where is the model number on a PURE SX?
Check the nameplate on the unit itself, and cross-reference it against your unit's O&M manual — we haven't verified one universal nameplate location across every SX production run, so we point you to the nameplate and manual rather than guess. If you can't locate or read it, contact us and we'll help.
This unit carries live steam on both the boiler-steam and humidification sides of its heat exchanger, along with line-voltage electrical controls. Service should be performed only by qualified personnel, following PURE Humidifier Co.'s O&M manual and your facility's lockout/tagout procedures.