Flanged Immersion Heaters
Flanged immersion heaters are high capacity electrical heating units made for tanks or pressurized vessels. They consist of multiple tubular heaters that are formed into hairpin and are welded or brazed to flanges. The immersion heater elements could be made of copper, steel, stainless steel or Incoloy sheath. Standard flanges are carbon steel rated for 150 lbs. Various types of electrical protection housing, built in thermostats and thermocouples are available
Specification of Immersion Heaters
| 150 Lbs. Flange detail rating | 300 Lbs Flange detail rating | |||||||||||
| Size | Max # of elements | Standard cold end | O.D. | Flange thickness | # Holes | Holes diameter | B.C. | O.D. | Flange thickness | # Holes | Holes Ø | B.C. |
| 2.5" | 3 | 5 1/2" | 7" | 7/8" | 4 | 3/4" | 5 1/2" | 7 1/2" | 1" | 8 | 7/8" | 5 7/8 |
| 3" | 6 | 5 1/2" | 7 1/2" | 15/16" | 4 | 3/4" | 6" | 8 1/4" | 1 1/8" | 8 | 7/8" | 6 5/8" |
| 4" | 9 | 5 1/2" | 9" | 15/16" | 8 | 3/4" | 7 1/2" | 10" | 1 1/4" | 8 | 7/8" | 7 7/8" |
| 5" | 9 | 6 3/4" | 10" | 15/16" | 8 | 7/8" | 8 1/2" | 11" | 1 3/8" | 8 | 7/8" | 9 1/4" |
| 6" | 18 | 6 3/4" | 11" | 1" | 8 | 7/8" | 9 1/2" | 12 1/2" | 1 7/16" | 12 | 7/8" | 10 5/8' |
| 8" | 30 | 6 3/4" | 13 1/2" | 1 1/8" | 8 | 7/8" | 11 3/4" | 15" | 1 5/8" | 12 | 1" | 13" |
| 10" | 48 | 10" | 16" | 1 3/16 | 12 | 1" | 14 1/4" | 17 1/2" | 1 7/8" | 16 | 1 1/8" | 15 1/4" |
| 12" | 60 | 10" | 19" | 1 1/4" | 12 | 1" | 17" | 20 1/2" | 2" | 16 | 1 1/4" | 17 3/4" |
| Bundle diameter to suit sch. 80 pipe | ||||||||||||
Typical Heating Applications Immersion Water Heaters
- HOT WATER TANKS
- BOILER HEATERS
- ASPHALT, PARAFFIN, WAX HEATERS
- OIL PRODUCT HEATERS
- CORROSIVE AND NON-CORROSIVE SOLUTIONS
- AIR AND GAS HEATERS
- HEAT TRANSFER EQUIPMENT
Selection of Immersion Heaters
Flanged immersion heaters can be used in different applications. In order to meet the heating requirements of a specific application and have a safe operation in the environment within which a heater operates, several factors should be taken into consideration in the design of flanged immersion heaters. The following are a number of criteria that should be considered:
- The pressure rating and the material of a flange.
- The sheath material of the tubular elements. Table 3 provides recommended tubular element sheathe and flange materials for different mediums.
- Operating temperature and watt density of tubular elements that are adequate to the material heated. Tables 2 & 3 provide maximum operating temperatures and watt densities that are recommended for heating various materials.
- Design watt density, flow velocity and outlet temperature are factors that contribute to the temperature level that tubular elements will attain. The table below shows the maximum temperatures that different sheath materials could be subjected to:
- for high wattages, multiple circuits are recommended
| Sheath Material | Maximum Temperature |
| Copper | 360°F (180°C) |
| Stainless Steel | 1200°F (650°C) |
| Steel | 750°F (400°C) |
| Incoloy | 1500°F (815°C) |
- Taking the environment within which the heater will operate into account, safety issues should be taken into consideration.
- Utilization of adequate temperature controlling devices, temperature and pressure high limit switches, low liquid level and flow controllers and other control/safety devices that will control the heating process and protect the heater from excessive heat.
- The classification of the electrical terminal box required (NEMA 1, NEMA 4, NEMA 7, NEMA 12 etc…).
- The level of the contamination that a heater will be exposed to.
- Electrical safety codes should be considered.
- The possible requirement of baffles that force a gas or a liquid to circulate around heating elements when flanged immersion heaters are used inside circulation tanks.
For more information in selecting Flanged immersion Water heaters please contact our technical specialists
| Application | Sheath Material | Screw plug material | Typical Watt Density w/in2 |
| Clean water | Copper | brass | 55-80 |
| Process water/Weak solution | Stainless Steel | Stainless Steel | 25-55 |
| Oil light | Steel | Steel | 20-25 |
| Oil medium | Steel | Steel | 12-15 |
| Corrosive solutions (basic) | Incoloy | Stainless Steel | 20-25 |
| Corrosive solutions (acidic) | Stainless Steel | Stainless Steel | 20-25 |
| Vegetable oil | Stainless Steel | Stainless Steel | 30-40 |
| Asphalt, tar, wax | Steel | Steel | 4-10 |
| Air | Incoloy | Steel | 25-30 |
THERMOSTATS AND THERMOCOUPLES
The thermostats used in flanged immersion heaters are the bulb and capillary style. The standard thermostat has 25A max capacity and could operate up to 240V. This thermostat is single pole/single throw style with a temperature range of 10-120ºC. The table below shows other ranges of thermostats that are available.
| Thermostat | Contact Operation | Temperature Range | Volts / Amps |
| T0 | SPST | 10ºC to 120ºC | 125V - 30A / 250V - 30A / 277V - 25A |
| T1 | SPST | -15,5ºC to 40ºC | 125V - 30A / 250V - 30A / 277V - 25A |
| T2 | SPST | 70ºC to 280ºC | 125V - 30A / 250V - 30A / 277V - 25A |
| T3 | SPST | 149ºC to 370ºC | 125V - 30A / 250V - 30A / 277V - 25A |
| T4 | SPST | 0ºC to 120ºC | 125V - 30A / 250V - 30A / 277V - 25A |
| T5 | DPST | 10ºC to 120ºC | max. 277V - max. 25A |
| T6 | DPST | -15,5ºC to 40ºC | max. 277V - max. 25A |
| T7 | DPST | 25,5ºC to 204,5ºC | max. 277V - max. 25A |
| T8 | DPST | 10ºC to 120ºC | max. 600V - max. 15A |
It should be noted that thermostats are only temperature controllers and should not be used as fail-safe high limit switches.
Built-in thermocouples could be used inside flanged immersion heaters to give more accurate temperature indications. Thermocouples could also be attached to one of the heating elements and used as high-temperature limiting devices.
Terminations of Immersion Heater Element
| Terminal Box Size | ||||||
| Flange | Without Thermostat | With Thermostat | ||||
| Size | Fig. # | Dim.A | Dim.B | Dim.A | Dim.B | |
| NEMA1 | 2.5" | 1 | - | 3'' | - | 4.5'' |
| 3" | 1 | - | 3'' | - | 4.5'' | |
| 4" | 1 | - | 4.5'' | - | 4.5'' | |
| 5" | 1 | - | 4.5'' | - | 4.5'' | |
| 6" | 1 | - | 4.5'' | - | 4.5'' | |
| 8" | 1 | - | 4.5'' | - | 4.5'' | |
| 10" | 1 | - | 7.5'' | - | 7.5'' | |
| 12" | 1 | - | 7.5'' | - | 7.5'' | |
| NEMA4 | 2.5" | 2 | 5 5/8" | 4 1/2" | 5 5/8" | 7 1/4" |
| 3" | 3 | 5 5/8" | 4 1/2" | 5 5/8" | 7 1/4" | |
| 4" | 3 | 6 11/16" | 7 1/4" | 6 11/16" | 7 1/4" | |
| 5" | 3 | 7 3/4" | 7 1/4" | 7 3/4" | 7 1/4" | |
| 6" | 3 | 8 3/4" | 7 1/4" | 8 3/4" | 7 1/4" | |
| 8" | 3 | 10 3/4" | 7 1/4" | 10 3/4" | 7 1/4" | |
| 10" | 3 | 11 7/8" | 7 1/4" | 11 7/8" | 7 1/4" | |
| 12" | 3 | 15 1/4" | 8'' | 15 1/4" | 8'' |
| NEMA7 | 2.5" | 4 | 4" | 9 1/4" | 4" | 11" |
| 3" | 4 | 4 1/2" | 9 1/4" | 4 1/2" | 11" | |
| 4" | 4 | 5 9/16" | 10 1/4" | 5 9/16" | 11 1/2" | |
| 5" | 4 | 6 5/8" | 10 3/4" | 6 5/8" | 12" | |
| 6" | 4 | 7 5/8" | 11" | 7 5/8" | 12 1/4" | |
| 8" | 4 | 9 5/8" | 13" | 9 5/8" | 13" | |
| 10" | 4 | 10 3/4" | 13 1/2" | 10 3/4" | 13 1/2'' | |
| 12" | 4 | 12 3/4" | 14 1/2" | 12 3/4" | 14 1/2'' |
Optional Features of IMMERSION WATER HEATERS
- NEMA 4 TERMINAL BOX
- NEMA 7 TERMINAL BOX
- 300 LB RATED FLANGES
- STAINLESS STEEL FLANGES
- SPECIAL TERMINAL BOX (STILTED, VENTED, STAINLESS STEEL, ETC…)
- BUILT-IN THERMOCOUPLES
- PASSIVATION
- BAFFLES
- THERMOSTATS WITH VARIOUS TEMPERATURE RANGES
- HIGH LIMIT TEMPERATURE DEVICES
