Convectronics Air Heater Instructions

Convectronics Operating Instructions for Air Heaters

Air Heaters from Convectronics

Triple Pass Convectronics Heater

Mounting

Mount heater in desired position. Care should be taken not to restrict exit end of heater. Mechanical shock and vibration should be minimized. Those heaters with quartz envelopes (Style 001) should be handled with a protective layer of cloth or paper to prevent contamination from finger prints. If quartz is contaminated, it should be cleaned with soap and water or mild solvent prior to operation of heater.


Air Supply

Connect a clean filtered and regulated air source to the inlet air connection of the heater. This air must be free of oils and other forms of contamination to prevent drastic reduction of heater life. A means of regulation is required so that the air flow rate can be adjusted and controlled which will allow maximum heater performance flexibility. A blower capable of operating at 1-2 PSI can be used to supply the 13” housing (Style 003). A compressed air source is required for the other heater types because of the higher pressures involved.

Electric Power Connection

Electric connections are made through ¼ x .032 male disconnects provided on Style 001 heaters or through the lead wires provided on Style 003 heaters. These connections should be made to the appropriate voltage source by means of a variable transformer so that voltage to the heater can be manually controlled. CONVECTRONICS offers a Power Control Module (#006-10062) which can be used in place of the transformer. This solid state device is rated up to 25 amps and offers infinitely variable phase control. CONVECTRONICS also offers temperature controllers to operate in conjunction with a solid state contactor (with adjustable voltage limiting). Because of the low mass and quick response of these heaters, use only phase angle power control (not zero cross) with
voltage limiting.

Operation

Consult performance curves before operation of heater. Air temperature and ultimately the heater life depend on the heater type, the air flow rate, and the applied voltage. Do not operate beyond the recommended limits. Maximum heater life will occur when the filament temperature does not exceed 1950° F.

Turn on air source and adjust to desired flow rate before applying voltage to heater. Air flow should not be stopped until after power has been turned off and heater has cooled. Pressure switches are available, which can be used to automatically turn off power if air flow is too low or stopped.

Turn on power source and increase voltage until desired temperature is reached. When automatic controls are used, set voltage limiting adjustment so that the maximum voltage does not exceed 100% of the normal steady state value required to maintain the desired conditions. Too high a setting will cause the heater to overshoot, cycle excessively and reduce its life. Do Not use zero cross systems. 

When a shield or flare is used with the Style 001 heaters the heater becomes more efficient and therefore the required power will be 10-20% less than normal.

Flameless Electric Air Heaters

Sords Electric
216-765-4230
www.sordselectric.com

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Heating with Compressed Air

Sords Electric and Convectronics offer Compressed (flameless) Air Heating, up to 1400 degrees F.

The energy (kW) requirement is calculated from the following formula:

 

KW = SCFM x (Texit – Tinlet) (ΔT) / 2500

SCFM = Air flow in Standard* Cubic Feet per Minute

Tinlet = Inlet Air Temperature (°F) (typically 70°F)

Texit = Desired Exit Air Temperature (°F)

[The temperature difference is also know as delta T (ΔT) ]

Example: Heating 10 SCFM from ambient temperature (70°F) to 800°F:

KW = 10 SCFM x (800°F – 70°F) / 2500 = 2.9 kW

Conversion Formulas:

(Liters per Minute)/28.3 = Cubic Feet per Minute

°C = 5/9 (°F – 32)

°F = 9/5°C + 32

Using an Air Heater:

If used properly, heater life of 5000 hours or greater can be expected. To ensure long heater life and safe operation, follow these guidelines. Also read and understand your heater Operating Manual before use. Failure to follow these guidelines can result in heater damage, failure, or personal injury. 

Air Sources:

In general, compressed air, and air from regenerative blowers may be used to supply Convectronics flameless air heaters. Your air source should be clean and dry. Dirt, grease, oil, or oil vapors, or corrosive or reactive gases will damage an air heater. Also, use air or inert gas only. Do not use with volatile or combustible gases.

Regenerative Blowers:

Regenerative blowers are compact and inexpensive clean air sources. They can provide large amounts of low-pressure air for your air heating system. 

Compressed Air:

Compressed air is commonly available in most factories. It is high-pressure regulated air (typically to 100psi), and often contains oil for lubricating pneumatic valves and equipment. You must filter this oil to prevent fouling and damage to Convectronics electric air heater elements.

When measuring compressed air flow rates, be sure you are measuring Standard CFM or Standard LPM units. The "Standard" means that the units are measured at standard temperature and pressure. Many flow meters are labeled SCFM, but this is incorrect at the higher pressures produced by compressed air. For accurate flow measurements, you must consult your flow meter manual for converting CFM to "Standard" CFM. In the diagram below, the flow meter reading (CFM) is converted to SCFM using a Dwyer ball-type flow meter conversion.

Controls:

A good control system is critical for long heater life. Before turning your control system on, you must have sufficient airflow through the heater before applying power. (Applies to heaters without over-temperature protection.) Only qualified individuals should install Convectronics heaters and controls. Follow all applicable electrical codes and use proper wiring, fusing and safety procedures.

Open-Loop (Manual) Control:

This simple method of control uses a manually operated power controller to apply a fixed voltage to the heating element. Using this system, the operator manually adjusts the controller to change heater temperature. Note that if the airflow is suddenly interrupted, the element could fail. The open-loop controller is generally used with Convectronicss Series heaters.

Closed-Loop (Feedback) Control:

A closed-loop heater control system uses a power controller, temperature controller, and thermocouple to provide a constant output temperature, regardless of changes in airflow. The temperature controller also provides a convenient display of your process air temperature.

Power Controller:

Phase angle fired SCR (Silicon Controlled Rectifier) power controls will provide the smoothest power regulation for  Air Heaters.

Temperature Controller:

Use only digital temperature controls with type-K thermocouple inputs. The temperature control output must match the input of the power control. (i.e. 4-20mA, or 0-10VDC).

A standard PID-type control with a wide proportional band setting will work best to minimize temperature overshoot. PID parameters may be auto-tuned, but only at temperatures well below the maximum of the heater. If the temperature rises too high during auto-tune, turn power off immediately.

When using a Solid State Relay power control, the temperature controller cycle time should be set for 100ms or less.

Thermocouple:

Use only a fine-wire (.030" max wire dia.), exposed-junction, type-K thermocouple placed within 1" of the heater exit for accurate temperature readings. Other thermocouple styles, or varying the distance from the heater exit will result in temperature measurement errors and/or heater failure.

Air Flow Conversions:

SCFM = SCFH / 60 = SLPM / 28.3
SLPM = SCFH / 2.12
SCMH = SCFH / 35.3
SCFM = (Pounds of Air Per Minute) / (.080 lbs/ft3)

SCFM = Standard Cubic Feet per Minute
SCFH = Standard Cubic Feet per Hour
SLPM = Standard Liters per Minute
SCMH = Standard Cubic Meters per Hour

Single Phase Wiring:

V = I x R (Volts = Amps x Ohms)
I = W / V (Amps = Watts / Volts)
W = V2/R (Watts = (Volts x Volts) / Ohms)
Use our Ohms Law Calculator

Three Phase Wiring:

Delta Configuration:

R = R1 = R2 = R3
Wdelta = 3(VL2)/R
Wdelta = 1.73 x VL x IL
IP = IL/1.73
VP = VL

Wye Configuration:

R = R1 = R2 = R3
Wwye = (VL2)/R = 3(VP2)/R
Wwye = 1.73 x VL x IP
IP = IL
VP = VL/1.73

Percent Loss of wattage with lower than rated voltages applied:

230-volt heater on 208 volts - 82% (18% loss)
240-volt heater on 208 volts - 75% (25% loss)
480-volt heater on 277 volts - 33% (66% loss)
480-volt heater on 440 volts - 84% (16% loss)
480-volt heater on 318 volts - 44% (56% loss)
550-volt heater on 480 volts - 76% (24% loss)

To convert KiloWatts to BTUs:

Multiply  KW x 3413 = BTUs

°F (Farenheit)	=	(9/5°C) + 32
°C (Celsius)	=	5/9 (°F - 32)

For application help, please call Sords Electric - 216-765-4230
www.sordselectric.com