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Quotes - Engineering - SalesDouble-Wall Plate Heat Exchangers
Turning a Silent Failure Into a Visible One
A single plate has one barrier between the two fluids. If it cracks, nothing about the exchanger announces it. A double-wall plate puts a vented gap in that path so the failure has somewhere visible to go.
Double-wall construction uses two plate sheets pressed together in place of a single plate. The gap between them is open at the edges. If either sheet develops a crack or pinhole, fluid travels along the gap and appears outside the unit rather than crossing into the other stream.
Where it is required. Potable water heating, where a heat transfer fluid must never reach drinking water. On-farm milk pre-cooling, where groundwater and milk must stay separate. Any duty where a utility fluid is toxic and the process fluid is not, or the reverse.
What it costs. The double sheet adds thermal resistance, so the exchanger needs more surface area for the same duty, and the unit is heavier. On a duty where a cross-contamination event means a recall or a regulatory conversation, that cost is rarely the expensive part of the decision.
On the farm. Double-wall construction removes the requirement to check groundwater annually, which is a direct and ongoing operating saving as well as a safety measure.
Part numbers. Every cataloged model, with the dimensions and ratings that separate them: Accu-Therm Double-Wall Part Numbers (14 part numbers).
Common to the Whole Series
Configuration
- Connection Type: Studded ports as standard, or lap-joint, weld-neck, ferrule and Victaulic ends
- Passes: Single pass standard; multi-pass available
- Plate Pattern: Chevron, welded double-wall pair
- Plate Thickness: 0.5 mm per sheet, two per wall
- Wall Construction: Double wall - vented welded plate pair
Materials
- Frame: Carbon steel, painted, or stainless to order; zinc-plated tie bolts
- Gasket: NBR or EPDM as standard; high-temperature EPDM, Viton/FKM or butyl; FDA/3-A grades
- Plate: 316 stainless standard, with 304, titanium, Hastelloy C-276 or SMO 254 available
Ratings
- Max Temperature: 410°F design; gasket dependent
- Max Working Pressure: 300 PSI (est.)
- Min Temperature: -20°F
Typical Specification
- Construction: Paired plate sheets with a vented interspace
- Leak path: To atmosphere at the plate edge, visible externally
- Typical duty: Potable water, dairy farm pre-cooling, toxic utility fluids
- Thermal effect: Additional resistance; more surface area required
- Materials: 316 stainless standard
- Farm duty: Double-wall construction available
- Regulatory: Removes annual groundwater checking on farm duty
- Inspection: Frame opens as normal for plate inspection
- Gaskets: Conventional gasket compounds
- Alternative: Single-wall plates where cross contamination is tolerable
| PRODUCT | CONSTRUCTION | MATERIALS | SUPPLY |
| Double-Wall Plate Heat Exchangers | Mueller factory built | 304 / 316 stainless | New equipment |
Double-Wall Plate Heat Exchangers
Specify It on Consequence, Not Probability
Plate failures are uncommon. The question is not the odds of a breach. It is what a breach costs you if it goes unnoticed until the end of the shift. If the answer involves potable water, product recall or a regulator, the arithmetic favors double-wall regardless of how reliable a single plate is.
The reverse also applies. On a closed glycol loop interchanging against tower water, double-wall construction adds surface area and cost for a consequence nobody would notice.
Accu-Therm Double-Wall Part Numbers
Plate & Frame Part Numbers
A double-wall plate is two plates pressed together with a vented gap between them. If either sheet is breached, the leak goes to atmosphere where somebody sees it rather than into the other fluid.
It is a construction, not a product line. Mueller sells double wall as a plate-pair option on standard frames. The AT4DW / AT10DW / AT20DW designations here are frame-plus-option strings rather than published catalog numbers — they are how the configuration is written down, and they are what you will see on a quotation.
Who decides you need it. The authority having jurisdiction, not us and not you. Settle that before ordering: a double-wall unit is physically larger for the same duty, so it changes the layout as well as the price.
Accu-Therm Double-Wall Part Numbers
The Cost Is Surface, Not Just Money
Two sheets in the heat path mean a lower transfer coefficient, which means more plates for the same duty. Expect a longer pack and a larger frame than the single-wall selection for the same numbers.
That is the trade, and it is worth making where a breach would mean a recall, a boil notice or a regulator. It is not worth making anywhere else.
Check the Vent Is Visible
The whole mechanism depends on somebody noticing. Install the unit so the vented interspace discharges somewhere a person walks past, and put it on the inspection round.
Part Numbers
| Part Number | Frame | Plate H | Plate W | Port | Surface Area | Max Flow | Also Written |
|---|---|---|---|---|---|---|---|
| AT4DW | C | C Frame (Cantilever) | 23" | 8" | 1" | 15 - 50 sq ft | 80 | AT 4DW, AT-04DW, AT-4DW, AT04DW |
| AT10DW | C, F | C Frame (Cantilever), F Frame (Intermediate) | 37" | 14" | 2" | 13 - 273 sq ft | 200 | AT 10DW, AT-10DW, AT10 DW, AT10-DW |
| AT20DW | C, F, B | C Frame (Cantilever), F Frame (Intermediate), B Frame (Beam) | 56" | 24" | 3" | 28 - 1,279 sq ft | 450 | AT 20DW, AT-20DW, AT20 DW, AT20-DW |
| AT35DW | C, F | C Frame (Cantilever), F Frame (Intermediate) | 52" | 13-1/2" | 2" | 30 - 600 sq ft | 200 | AT 35DW, AT-35DW, AT35 DW, AT35-DW |
| AT40DW | F, B | F Frame (Intermediate), B Frame (Beam) | 70-1/4" | 27" | 4" | 99 - 2,292 sq ft | 800 | AT 40DW, AT-40DW, AT40 DW, AT40-DW |
| AT55DW | F, B | F Frame (Intermediate), B Frame (Beam) | 77-1/2" | 18-1/2" | 4" | 80 - 1,600 sq ft | 800 | AT 55DW, AT-55DW, AT55 DW, AT55-DW |
| AT60DW | F, B | F Frame (Intermediate), B Frame (Beam) | 82-1/8" | 27" | 4" | 110 - 2,500 sq ft | 800 | AT 60DW, AT-60DW, AT60 DW, AT60-DW |
| AT75DW | B | B Frame (Beam) | 75-5/8" | 25-1/2" | 6" | 120 - 2,900 sq ft | 1800 | AT 75DW, AT-75DW, AT75 DW, AT75-DW |
| AT80DW | B, LB, RB | B Frame (Beam), LB Frame, RB Frame | 85" | 36" | 6" | 181 - 4,186 sq ft | 1800 | AT 80DW, AT-80DW, AT80 DW, AT80-DW |
| AT120DW | B | B Frame (Beam) | 104-1/2" | 36" | 6" | 230 - 5,200 sq ft | 1800 | AT 120DW, AT-120DW, AT120 DW, AT120-DW |
| AT130DW | B | B Frame (Beam) | 106-3/4" | 43" | 10" / 12" | 413 - 9,804 sq ft | 6600 | AT 130DW, AT-130DW, AT130 DW, AT130-DW |
| AT402DW | C, F | C Frame (Cantilever), F Frame (Intermediate) | 39-1/4" | 27" | 4" / 6" | 16 - 106 sq ft | 1150 | AT 402DW, AT-402DW, AT402 DW, AT402-DW |
| AT405DW | C, F, B | C Frame (Cantilever), F Frame (Intermediate), B Frame (Beam) | 56" | 27" | 4" | 48 - 1,495 sq ft | 800 | AT 405DW, AT-405DW, AT405 DW, AT405-DW |
| AT805DW | B | B Frame (Beam) | 63" | 36" | 6" | 105 - 2,440 sq ft | 1800 | AT 805DW, AT-805DW, AT805 DW, AT805-DW |
14 part numbers. Figures marked (est.) are engineering estimates rather than Mueller published values — ask us to confirm before designing to one. Everything else traces to the source named in the catalog record.
Specifying the Double-Wall
Since double wall is a plate option on standard frames, a conversion is sometimes possible, though the pack gets longer for the same duty. Whether it fits comes down to the existing carrying bar and tie bolts and how many extra plates the double sheet demands. Send the frame part number, the present plate count and the duty, and we will rate the double-wall pack against that frame length.
It can be either, and the location tells you which. A gasket weep appears at the gasket line between plates, while a breached sheet discharges from the vented edge of a welded plate pair. Note which stream it is and exactly where it shows, then open the pack and test the suspect pair before the unit goes back onto potable water or milk.
The series lists a maximum working pressure of 300 PSI, and that figure is marked as an estimate. Treat it as a planning number and send the actual design pressure on each side so the rating can be confirmed before the selection is fixed. On potable water heating, the street supply pressure and any booster pump usually set the worst case, so include them.
Access is unchanged, because the frame opens and the pack comes apart as it would on a single-wall unit. What differs is that each welded pair is handled as one piece, and the gap between its two sheets can not be cleaned or looked into. A pair suspected of a breach is tested and replaced whole rather than repaired.
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