Watlow Immersion Heater

Watlow Immersion Heater

Core Product System and Classification

（1） Spiral plug immersion heater (WATROD) ™  and FIREBAR ®  Screw Plug）

1. Product positioning and applicable scenarios

Specially designed for direct immersion heating of liquids, it can be used for heating various oils, heat transfer solutions, and other liquids. Typical applications include industrial rinse tanks, steam degreasing equipment, hydraulic oil heating, antifreeze (ethylene glycol) solution heating, and other scenarios. For example, in clean water heating scenarios, a 1-inch NPT screw plug paired with WATROD components can meet the heating needs of different water qualities such as deionized water and drinking water.

2. Structure and Component Characteristics

Heating element: It includes WATROD circular tubular element and FIREBAR flat tubular element, both of which adopt a hairpin bending design. According to the compatibility between the element sheath and the plug material, they are fixed on the spiral plug by welding or brazing. Among them, WATROD hair clips undergo recompacted treatment to maintain magnesium oxide (MgO) density, dielectric strength, heat transfer efficiency, and service life.

Terminal box: The standard configuration is a universal terminal box, and optional types such as moisture-proof, explosion-proof, and moisture-proof explosion-proof composite are provided to adapt to different environmental requirements. For example, in humid or explosive gas environments, corresponding protective terminal boxes can be selected, and the terminal boxes can be rotated for easy connection with existing conduits.

Auxiliary components: Some models are equipped with integral thermocouple sleeves, which facilitate the insertion and replacement of temperature sensors without the need to drain the heated fluid; Optional thermostats can achieve convenient process temperature regulation, such as SPST (single pole single throw) and DPST (double pole single throw) types, with a temperature control range covering 30-550 ° F.

3. Key performance parameters

Power and Voltage: The power density can reach up to 120 W/in ² (18.6 W/cm ²), with a power range from 250 watts to 38 kilowatts, voltage adaptation to 120-480VAC, and UL certification ®  CSA component certification supports up to 480VAC and 600VAC respectively.

Sheath material and temperature: Different sheath materials correspond to different maximum operating temperatures. Alloy 800/840 sheath has a maximum temperature of 1600 ° F (870 ° C), 304/316 stainless steel sheath has a maximum temperature of 1200 ° F (650 ° C), and steel sheath has a maximum temperature of 750 ° F (400 ° C), which can be selected according to the temperature requirements of the heating medium.

Size specifications: Spiral plug sizes include NPT specifications such as 3/4 inch, 1 inch, 1.25 inch, 2 inch, 2.5 inch, and some also support European G-type (brass material) and BSP type (stainless steel material) thread standards. Taking a 1-inch NPT plug as an example, it can be paired with 0.260-inch and 0.315-inch WATROD components; The 2.5-inch NPT plug can be compatible with 0.430-inch, 0.475-inch WATROD components and 1-inch FIREBAR components.

4. Customization and accessory options

Material customization: In addition to standard sheath and plug materials, special sheath materials such as Hastelloy C276 and titanium alloy, as well as plug materials such as 304H, 316H, and 321 stainless steel, can also be provided to meet the needs of highly corrosive or special working conditions.

Functional accessories: optional indicator lights (PL10 and PL11 models), PL10 is compatible with up to 250VAC and equipped with 6-inch (152mm) leads; PL11 is compatible with 480VAC and equipped with 4-inch (102mm) leads, which can visually display the power on/off status of the heater. In addition, an adapter for spiral plugs to flanges is also provided, which facilitates the replacement of spiral plug heaters with flange heaters. The adapter material is mostly steel, and different specifications correspond to different shipping weights. For example, the shipping weight of the 1.25 inch to 3-inch to 150 # adapter is 13 pounds (5.9kg).

（2） ANSI Flange Immersion Heater (WATROD and FIREBAR ANSI Flange)

1. Product features and applicable scenarios

Suitable for scenarios that require high-power heating and high installation stability, such as liquid heating in large storage tanks and industrial reactors. It can handle various media such as clean water, process water, heavy oil, asphalt, etc. Its flange structure ensures sealing performance under high pressure conditions, with pressure ratings ranging from 150 pounds, 300 pounds, 600 pounds, etc.

2. Core parameters and structure

Power and density: The power density can reach up to 100 W/in ² (15.5 W/cm ²), providing higher heating power to meet the rapid heating needs of large capacity media.

Flanges and components: Flange sizes range from 2 inches to 48 inches, suitable for different equipment interfaces; The heating element also includes WATROD and FIREBAR types, and the connection method between the element and the flange is determined based on material compatibility to ensure pressure sealing effect.

Protection and Control: The terminal box type is similar to the screw plug type, supporting universal, moisture-proof, explosion-proof, etc. It can also be matched with thermocouples and thermostats to achieve precise temperature control and monitoring.

3. Customization and adaptation

Support customization of flange size, pressure rating, and component arrangement according to customer needs. We can also provide flanges and components made of special materials to cope with harsh working conditions such as corrosion or high temperatures. For example, when dealing with highly corrosive solutions, flanges and components made of Hastelloy material can be used.

Typical application scenarios and adaptation solutions

（1） Water heating

1. Heating of clean water

Product selection: Common 1-inch, 1.25-inch, 2-inch, 2.5-inch NPT spiral plug heaters, paired with WATROD or FIREBAR components. Taking a 1-inch NPT screw plug as an example, if Alloy 800 sheath components are used, the power density can reach 60 W/in ² (9.3 W/cm ²), and the power can range from 0.5kW to 4kW at 240VAC. It is suitable for small water tanks, laboratory water heating and other scenarios.

Configuration options: Universal terminal box or moisture-proof terminal box can be selected, paired with SPST thermostat (temperature range 30-250 ° F or 175-550 ° F), such as models BCN4J1S2 (Type 2 temperature range) and BCN4J1S3 (Type 3 temperature range), both of which support next day shipping (RS identification).

2. Heating of deionized water/desalinated water

Material adaptation: Due to the possible corrosiveness of deionized water, components with 316 stainless steel plugs and 316 stainless steel sheaths are usually selected, such as 2.5-inch NPT spiral plug heater, model BLR77L3S4, sheath material of 316 stainless steel, power 3kW, voltage 240VAC, power density 9.3 W/cm ², which can effectively resist the corrosion of deionized water and ensure long-term stable operation.

Control and Protection: K-type thermocouples can be equipped for precise monitoring of process temperature. The terminal box is selected as moisture-proof and explosion-proof, suitable for environments that may be humid or have slightly corrosive gases.

3. Heating of process water

Product type: Depending on the flow rate and heating requirements of the process water, a 1.25-inch NPT FIREBAR element heater or a 2-inch NPT WATROD element heater can be selected. For example, a 1.25-inch NPT FIREBAR heater, model BDNF13A27S5A, with a power of 2.0kW, a voltage of 240VAC, and a power density of 7 W/cm ², is suitable for heating medium flow process water; 2-inch NPT WATROD heater, model BGS79J6S4, power 1.0kW, voltage 120/240VAC, compatible with different process equipment interfaces.

Installation requirements: It is necessary to ensure that the heater is installed on the path of the process water flow, and that the components are completely immersed in the water to avoid dry burning. At the same time, the installation angle of the components should be adjusted according to the direction of the water flow to improve heat transfer efficiency.

（2） Heating of oils and viscous media

1. Heating of light oil and heat transfer oil

Power density control: Due to the relatively low heat transfer efficiency of oils, heaters with medium power density, such as 23 W/in ² (3.6 W/cm ²), are usually selected. Taking the 1-inch NPT WATROD heater as an example, model BCS6J1S, with steel sheath material, power of 0.25kW, voltage of 120VAC, suitable for heating lightweight lubricating oil; 1.25-inch NPT WATROD heater, model BES6G6S, power 0.5kW, voltage 120/240VAC, can be used for heating heat transfer oil.

Structural design: Some models use flat FIREBAR components, which can increase the contact area with oil and improve heating uniformity, such as the 1.25-inch NPT FIREBAR heater, model BDNF 16G12S5A, power 1.7kW, voltage 240VAC, suitable for small oil tank heating.

2. Intermediate oil heating

Low power density adaptation: Medium quality oil has poor fluidity and requires the use of a lower power density heater, such as 15 W/in ² (2.3 W/cm ²), to avoid local overheating and carbonization of the oil. For example, a 1.25-inch NPT FIREBAR heater, model BDNF 13A29S5A, with a power of 0.67kW and a voltage of 240VAC, is suitable for heating medium lubricating oil; 2-inch NPT WATROD heater, model BHN79N12S4, power 1.0kW, voltage 240VAC, suitable for heating medium quality oil storage tanks.

Temperature control: Equipped with DPST thermostat with a temperature control range of 60-250 ° F to prevent excessive oil temperature. At the same time, a low level sensor can be selected to avoid dry burning and damage to the heater due to low oil level.

3. Heating of heavy oil, asphalt, and # 6 fuel oil

Extremely low power density: This type of medium has extremely high viscosity and poor heat transfer efficiency, requiring the use of heaters with extremely low power density, such as 8 W/in ² (1.3 W/cm ²). For example, a 1.25-inch NPT FIREBAR heater, model BDNF 16G22S5A, with a power of 0.43kW and a voltage of 240VAC, is suitable for the initial stage of asphalt heating; 2.5-inch NPT WATROD heater, model BLS717E12S4, with a power of 1.0kW and a voltage of 240VAC, can be used for heating and insulation of # 6 fuel.

Structure and Installation: Heaters are usually designed with long components to increase the contact length with the medium and improve heating efficiency. At the same time, the flowability of the medium should be considered during installation to avoid the heater being covered by sediment and affecting heat transfer. In addition, explosion-proof terminal boxes can be selected to adapt to the combustible gas environment that may be generated during the heating process of heavy oil.

（3） Heating in other special scenarios

1. Forced air heating

Product type: Multiple choice 1.25-inch NPT WATROD element heater, sheath material is 304 stainless steel, power 1.0-2.0kW, voltage 120/240VAC, such as model BEN13G6S, power 1.0kW, voltage 120/240VAC, can be used with a fan to achieve forced air circulation heating, suitable for winter insulation in small workshops and equipment rooms.

Protection requirements: The terminal box should be dust-proof to prevent dust from entering and affecting electrical performance. At the same time, the installation position of the heater should be away from flammable materials to prevent fire risks.

2. Heating of corrosive solutions

Special material selection: The sheath material is made of Hastelloy C276 or titanium alloy, and the plug material is 316 stainless steel to resist corrosion from solutions. For example, a 2.5-inch NPT WATROD heater with a sheath material of Hastelloy C276, a power of 3.0kW, a voltage of 240VAC, suitable for heating acidic solutions; 1.25-inch NPT WATROD heater with titanium alloy sheath material, power of 0.7kW, voltage of 120VAC, suitable for heating alkaline solutions.

Sealing and Protection: The connection between components and plugs adopts a special welding process to ensure sealing performance and prevent solution from infiltrating and corroding electrical components. The terminal box adopts a fully sealed moisture-proof and explosion-proof type to further improve the protection level.

Ordering Information and Delivery

（1） Model coding rules

The model code contains multiple parameter information. Taking the screw plug heater as an example, such as "BCN4J1S2":

BC ": represents the basic series (screw plug type, WATROD component);

N ": indicates the material of the plug (brass);

4 ": corresponds to size" B "(4.5 inches, 114mm);

J ": Component diameter (0.315 inches, 8mm);

1: Voltage (120VAC);

S ": Terminal box type (universal type);

2 ": Thermostat type (Type 2, temperature range 30-250 ° F).

The core configuration of the heater can be quickly identified through model coding, facilitating accurate ordering.

（2） Delivery cycle

Standard products: Products with the "RS" logo support next day shipping, such as most 1-inch and 1.25-inch NPT spiral plug heaters, meeting emergency needs. For example, models BCN4J1S2, BDNF 13A27S5A, etc. have sufficient inventory and can be arranged for shipment the next day after placing an order.

Customized products: Customized products that require special materials, sizes, or functions, with a delivery cycle determined by specific needs, usually 2-4 weeks. For example, the selection of Hastelloy C276 sheathed heaters, customized size flange heaters, etc. require material procurement, processing and manufacturing, testing and other processes, with a relatively long delivery cycle.

（3） Accessories ordering

Sealing accessories: Multiple materials of gaskets are available, such as rubber gaskets (suitable for water-based media), asbestos free gaskets (suitable for general industrial scenarios), and wound gaskets (suitable for high-pressure conditions), which can be selected according to the usage scenario and pressure level of the heater.

Installation accessories: including lifting lugs (for easy installation and disassembly of large heaters), baffles (to prevent direct impact of media on components, protect components), extended lead thermocouples (for remote temperature monitoring), etc., can be ordered separately according to actual installation needs.

Key points for installation and maintenance

（1） Installation requirements

Immersion depth: The unheated section of the heater needs to be completely immersed in the heated medium, ensuring at least 1 inch (25mm) of unheated section is inside the medium to prevent overheating and damage to the unheated section. For example, in clean water heating, the unheated section of a 1-inch NPT heater needs to be completely submerged below the water surface to avoid exposure to air.

Installation position: The heater should be installed in the lower area of the container, but higher than the sediment layer at the bottom of the container, to prevent sediment from covering the components and affecting heat transfer. At the same time, it facilitates natural convection of the medium and improves heating uniformity. For containers with stirring devices, the heater should be installed within the range of the stirring blades to further enhance heat transfer.

Flow direction and angle: When installing the FIREBAR element heater, the installation angle of the element needs to be determined based on the flow direction of the medium, usually at a certain angle (such as 45 °) to reduce pressure loss and improve heat transfer efficiency. For example, in process water heating, FIREBAR components should be installed in the direction of water flow to avoid direct impact of water flow on the components causing wear.

Electrical connection: The electrical connection must comply with the national electrical specifications, and the specifications of the power cord should be selected according to the power and voltage of the heater to ensure sufficient current carrying capacity, while also taking waterproof and dustproof measures. The installation of terminal boxes should avoid direct exposure to rainwater or corrosive liquids. If installed outdoors or in humid environments, additional protective measures should be taken.

（2） Maintenance points

Regular cleaning: Disassemble the heater regularly (e.g. every 3 months), clean the surface of the components of dirt, sediment, and other impurities to prevent affecting heat transfer efficiency. When cleaning, a soft bristled brush or specialized cleaning agent can be used to avoid scratching the protective cover of the component with sharp tools, which can lead to increased corrosion.

Status check: Check whether the protective sheath of the component is corroded, deformed, leaking, etc. If the sheath is found to be damaged, the component should be replaced in a timely manner to prevent the medium from infiltrating the interior and damaging the electrical components. At the same time, check the sealing performance of the terminal box to ensure that no moisture or dust enters, whether the electrical connections are tight, and whether there are any looseness or oxidation phenomena.

Calibration of temperature monitoring equipment: Regularly (e.g. every 6 months) calibrate temperature monitoring and control equipment such as thermostats and thermocouples to ensure the accuracy of temperature measurement and control. If the accuracy deviation of the equipment exceeds the allowable range, it should be adjusted or replaced in a timely manner.

Maintenance records: Establish a maintenance record file to record the maintenance time, content, problems discovered, and solutions taken for each maintenance, in order to track the usage status of the heater, predict possible failures in advance, and develop a reasonable maintenance plan.

Safety precautions

Prevent dry burning: Before running the heater, it is necessary to ensure that the medium has reached the specified liquid level and that the components are completely immersed in the medium. It is strictly prohibited to start the heater without medium or with insufficient medium liquid level to avoid dry burning causing component damage or even fire. Low level sensor can be installed to achieve low level protection. When the liquid level is lower than the set value, the heater power supply will be automatically cut off.

Explosion proof safety: In environments with explosive gases or dust, explosion-proof terminal boxes must be selected, and the installation of heaters must comply with explosion-proof regulations to avoid electrical sparks causing explosions. Regularly inspect the explosion-proof sealing surface. If damage or aging is found on the sealing surface, the sealing components should be replaced in a timely manner to maintain the explosion-proof performance.

Temperature control: It is strictly prohibited to operate beyond the maximum working temperature of the heater. Based on the characteristics and process requirements of the heated medium, the temperature control of the thermostat should be set reasonably to avoid overheating, decomposition or deterioration of the medium. For heat sensitive media, an over temperature protection device should be equipped to further improve safety.

Electrical safety: The grounding of the heater must be reliable to prevent leakage accidents. When conducting maintenance or overhaul, it is necessary to first cut off the power supply and hang a "Do Not Close" sign to avoid accidental power on and personal injury.