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Accu-Therm Plate Heat Exchanger

Simple fluids, viscous solutions and light particulates, one frame

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Mueller Accu-Therm gasketed plate and frame heat exchanger

Accu-Therm Series

Product Type Style Rating
Heat Exchanger Plate & Frame Gasketed 350 PSI / 410°F

The original Accu-Therm, and the unit most of this line is built from. It handles simple fluids, viscous solutions and light particulates in the same frame, with the plate pattern doing the tuning.

Twenty-six cataloged frame sizes, AT4 through AT161FF. The table further down carries every one of them with the dimensions and ratings that separate them.

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Common to the Whole Series

Configuration

  • Connection Type: Studded port standard; lap-joint, weld-neck, ferrule, Victaulic
  • Mounting: Floor mounted frame
  • Passes: Single pass standard; multi-pass available
  • Plate Thickness: 0.5 mm standard
  • Wall Construction: Single wall gasketed

Materials

  • Frame: Painted carbon steel; stainless optional. Zinc-plated compression bolts
  • Gasket: NBR or EPDM standard; High-Temp EPDM, Viton/FKM, Butyl. FDA/3-A
  • Plate: 316 SS standard; 304 SS, Titanium, Hastelloy C-276, SMO 254 optional

Ratings

  • Max Temperature: 410°F design; 302°F - 329°F gasket limit
  • Min Temperature: -20°F (MDMT 32°F typical)
  • Test Pressure: 1.3 x MAWP

Typical Specification

  • Type: Gasketed plate and frame, counterflow
  • Plate materials: 304 and 316 stainless, titanium, Hastelloy, Incoloy
  • Gasket compounds: Nitrile (NBR), EPDM, silicone, Viton/FKM, butyl
  • Plate area: 0.5 to 51 square feet per plate
  • Corrugation styles: Seven patterns, mixable within one pack
  • Approach temperature: 2 to 3°F achievable
  • Typical pressure: 75 to 300 psig; higher available
  • Ports: Studded standard, linings available
  • Connections: Lap-joint, weld-neck, ferrule, Victaulic; mixable
  • Frames: Standard or custom drop-in for existing installations
PRODUCT CONSTRUCTION MATERIALS SUPPLY
Accu-Therm Plate Heat Exchanger Mueller factory built 304 / 316 stainless New equipment

Accu-Therm Plate Heat Exchanger

The Original Mueller Plate Exchanger

The standard Accu-Therm is an industrial workhorse. It appears in HVAC plant rooms, chemical process trains, oil and gas facilities, refrigeration systems and food plants, and the reason is that one frame family covers an enormous range of duty simply by changing plate count, plate pattern and materials.

Seven corrugation patterns. The plate pattern sets the balance between thermal efficiency and pressure drop. A high-theta plate extracts more heat per pass and costs more pressure drop; a low-theta plate does the reverse. Because patterns can be mixed within one pack, the pack can be tuned rather than compromised.

Sizes and connections. Individual plate heat transfer areas run from 0.5 up to 51 square feet, so the same design principle serves a small skid and a large plant utility duty. Studded ports are standard and can be fully lined to protect the frame from erosion and corrosion. Lap-joint, weld-neck, ferrule and Victaulic connections are available and can be mixed on one unit.

Testing and inspection. Each circuit is tested independently at full design pressure before the unit ships. In service, removing the compression bolts and sliding back the movable end frame exposes 100 percent of the heat transfer surface for inspection.

Part numbers. Every cataloged model, with the dimensions and ratings that separate them: Accu-Therm Series Part Numbers (41 part numbers).

Mueller Accu-Therm plate heat exchanger with studded ports and a corrugated plate pack

Accu-Therm Plate Heat Exchanger

Choosing the Plate Pattern

This is where most of the engineering happens and where most of the difference in a quotation comes from. Two units with the same surface area can behave very differently depending on the corrugation depth and angle.

Give us the allowable pressure drop on each side along with the thermal duty. Without it, the software will happily produce a unit that makes the temperature and cannot be pumped through, or a unit with far more surface area than the duty needs.

Mixing Connection Styles

It is common for one side of a unit to be sanitary and the other to be plant utility. Ferrule connections on the product side and flanged connections on the water side is a normal, sensible arrangement and costs less than making everything sanitary.

Studded ports are the standard arrangement and can be lined where the fluid is erosive or the frame material would otherwise be attacked.

Accu-Therm Series Part Numbers

Plate & Frame Part Numbers

The Accu-Therm number is the frame, not the unit. An AT20 with forty plates and an AT20 with four hundred are the same part number and very different exchangers — the frame sets the plate size, the port size and the maximum pack length, and the plate count inside it sets the duty.

Reading the number. The digits are a size designation, not a plate count and not a capacity. AT4 is the smallest frame in the range and AT161 the largest. A letter suffix adds a construction: W for semi-welded, FF for free-flow, DW for double-wall, SAN for sanitary.

What to send us. If you are replacing a unit, the part number off the nameplate plus the plate count is enough to quote a match. If you are specifying a new one, send the duty instead and let the frame fall out of the calculation.

Surface Area Is a Range, Not a Number

The surface area column gives the span between the minimum and maximum plate count that frame accepts. Where you land inside that range is the selection. A frame quoted near the top of its range has no headroom left, which is worth knowing at purchase rather than at the next debottleneck.

Maximum flow is the frame's port limit, not a duty. Hitting it means the port velocity is at the top of what the design allows, and pressure drop will be doing the same.

Accu-Therm plate pack, gaskets and frame components

Frame Style C, F and B

The frame type code in the table is the style, and it decides how the unit mounts and how far the pack can grow. C is the compact cantilever frame, for the small sizes and tight plant rooms. F is the intermediate frame with a support column. B is the full frame with the longest carrying bar and the largest plate counts.

Some sizes are offered in more than one style, which is why the column sometimes reads "C, F" or "C, F, B". If pack headroom matters to you — and it should, because adding plates later is far cheaper than buying a second unit — say so and we will quote the frame that leaves you room.

Specifying Accu-Therm

It is the shop test pressure, 1.3 times the maximum allowable working pressure, applied to each circuit separately before shipment. Testing one side at a time proves the plates hold between the two streams as well as against atmosphere. If a field hydrotest is planned after installation, keep it at or below that figure, because overpressure can deform plates and unseat gaskets.

The design can be built for metal temperatures down to -20°F, but most units are stamped with a 32°F minimum design metal temperature. If a glycol stream or an outdoor winter startup can pull the metal below freezing, say so at order. A lower MDMT has to be specified and stamped in from the start, and it cannot be claimed after the unit is built.

Multi-pass sends a stream back through the pack more than once, which raises velocity and thermal length when one side has a small flow or a long temperature change. The cost is that connections end up on the movable frame as well as the fixed one, so pipework at that end has to come off before the pack can open. Single pass keeps every connection on the fixed frame, which is why it is the default.

These are for chemistry that 316 cannot survive and titanium does not suit, which mostly means acids. SMO 254 is a high-molybdenum stainless with far better chloride pitting resistance than 316, while C-276 is a nickel alloy for strong reducing and oxidizing acids. Both carry a real price premium, so send the full stream analysis and temperature and let the material follow from that.

The frame and plates are rated to 410°F, but every elastomer has a lower ceiling, and the standard compounds stop between 302°F and 329°F. The gasket is therefore the real temperature limit of a gasketed Accu-Therm. A stream above that window calls for a different construction, not a tougher seal, so give us the peak temperature on each side, upset conditions included.

Accu-Therm Units

Part NumberFramePlate HPlate WPortSurface AreaMax FlowAlso Written
AT4C | C Frame (Cantilever)23"8"1"15 - 50 sq ft80AT 4, AT-04, AT-4, AT04
AT5C | C Frame (Cantilever)31-1/8"7-1/2"1"18 - 70 sq ft80AT 5, AT-05, AT-5, AT05
AT10C, F | C Frame (Cantilever), F Frame (Intermediate)37"14"2"13 - 273 sq ft200AT 10, AT-10
AT20C, F, B | C Frame (Cantilever), F Frame (Intermediate), B Frame (Beam)56"24"3"28 - 1,279 sq ft450AT 20, AT-20
AT35C, F | C Frame (Cantilever), F Frame (Intermediate)52"13-1/2"2"30 - 600 sq ft200AT 35, AT-35
AT40F, B | F Frame (Intermediate), B Frame (Beam)70-1/4"27"4"99 - 2,292 sq ft800AT 40, AT-40
AT55F, B | F Frame (Intermediate), B Frame (Beam)77-1/2"18-1/2"4"80 - 1,600 sq ft800AT 55, AT-55
AT60F, B | F Frame (Intermediate), B Frame (Beam)82-1/8"27"4"110 - 2,500 sq ft800AT 60, AT-60
AT75B | B Frame (Beam)75-5/8"25-1/2"6"120 - 2,900 sq ft1800AT 75, AT-75
AT80B, LB, RB | B Frame (Beam), LB Frame, RB Frame85"36"6"181 - 4,186 sq ft1800AT 80, AT-80
AT95B | B Frame (Beam)107-3/4"25-1/2"6"170 - 4,000 sq ft1800AT 95, AT-95
AT120B | B Frame (Beam)104-1/2"36"6"230 - 5,200 sq ft1800AT 120, AT-120
AT130B | B Frame (Beam)106-3/4"43"10" / 12"413 - 9,804 sq ft6600AT 130, AT-130
AT150B | B Frame (Beam)109-3/8"34-1/2"8"300 - 7,000 sq ft3200AT 150, AT-150
AT156B | B Frame (Beam)87-1/2"34-1/2"8"240 - 5,600 sq ft3200AT 156, AT-156
AT165B | B Frame (Beam)126-3/8"45-3/8"14"500 - 12,000 sq ft9500AT 165, AT-165
AT180B | B Frame (Beam)126"56"14"600 - 14,000 sq ft9500AT 180, AT-180
AT250B | B Frame (Beam)134"57"16" / 20"972 - 17,309 sq ft17300AT 250, AT-250
AT402C, F | C Frame (Cantilever), F Frame (Intermediate)39-1/4"27"4" / 6"16 - 106 sq ft1150AT 402, AT-402
AT405C, F, B | C Frame (Cantilever), F Frame (Intermediate), B Frame (Beam)56"27"4"48 - 1,495 sq ft800AT 405, AT-405
AT426C, F | C Frame (Cantilever), F Frame (Intermediate)43-3/4"18-1/2"4"40 - 900 sq ft800AT 426, AT-426
AT805B | B Frame (Beam)63"36"6"105 - 2,440 sq ft1800AT 805, AT-805
AT510B | B Frame (Beam)90"30"6"200 - 4,400 sq ft1800AT 510, AT-510
AT1306B | B Frame (Beam)84-3/4"43"10" / 12"262 - 6,209 sq ft6600AT 1306, AT-1306
AT1309B | B Frame (Beam)99-1/2"43"10" / 12"363 - 8,622 sq ft6600AT 1309, AT-1309
AT2508B | B Frame (Beam)120"57"16" / 20"860 - 15,308 sq ft17300AT 2508, AT-2508
AT4PC | C Frame (Cantilever)23"8"1"15 - 50 sq ft80AT 4P, AT-04P, AT-4P, AT04P
AT20PC, F, B | C Frame (Cantilever), F Frame (Intermediate), B Frame (Beam)56"24"3"28 - 1,279 sq ft450AT 20P, AT-20P, AT20 P, AT20-P
AT40MF, B | F Frame (Intermediate), B Frame (Beam)70-1/4"27"4"99 - 2,292 sq ft800AT 40M, AT-40M, AT40 M, AT40-M
AT40PF, B | F Frame (Intermediate), B Frame (Beam)70-1/4"27"4"99 - 2,292 sq ft800AT 40P, AT-40P, AT40 P, AT40-P
AT40LF, B | F Frame (Intermediate), B Frame (Beam)70-1/4"27"4"99 - 2,292 sq ft800AT 40L, AT-40L, AT40 L, AT40-L
AT60MF, B | F Frame (Intermediate), B Frame (Beam)82-1/8"27"4"110 - 2,500 sq ft800AT 60M, AT-60M, AT60 M, AT60-M
AT75PB | B Frame (Beam)75-5/8"25-1/2"6"120 - 2,900 sq ft1800AT 75P, AT-75P, AT75 P, AT75-P
AT75XB | B Frame (Beam)75-5/8"25-1/2"6"120 - 2,900 sq ft1800AT 75X, AT-75X, AT75 X, AT75-X
AT80MB, LB, RB | B Frame (Beam), LB Frame, RB Frame85"36"6"181 - 4,186 sq ft1800AT 80M, AT-80M, AT80 M, AT80-M
AT80PB, LB, RB | B Frame (Beam), LB Frame, RB Frame85"36"6"181 - 4,186 sq ft1800AT 80P, AT-80P, AT80 P, AT80-P
AT120MB | B Frame (Beam)104-1/2"36"6"230 - 5,200 sq ft1800AT 120M, AT-120M, AT120 M, AT120-M
AT130MB | B Frame (Beam)106-3/4"43"10" / 12"413 - 9,804 sq ft6600AT 130M, AT-130M, AT130 M, AT130-M
AT156XB | B Frame (Beam)87-1/2"34-1/2"8"240 - 5,600 sq ft3200AT 156X, AT-156X, AT156 X, AT156-X
AT405MC, F, B | C Frame (Cantilever), F Frame (Intermediate), B Frame (Beam)56"27"4"48 - 1,495 sq ft800AT 405M, AT-405M, AT405 M, AT405-M
AT805MB | B Frame (Beam)63"36"6"105 - 2,440 sq ft1800AT 805M, AT-805M, AT805 M, AT805-M

41 part numbers.

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