PT9999

PT Series Ceramic Fiber Lined Electric And Gas Fired Pit Furnaces Up To 2400°F (1315°C)

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LOCKED BY SERIES
Type Pit
Power Source Electric Or Gas
Loading Top
Uniformity AMS Class 2 (± 10ºF / 6ºC)
Atmosphere Air
Lining Ceramic Fiber

Applications

LOCKED BY SERIES

Description

The PT Series are ceramic fiber lined pit furnaces. They can be designed for either air or controlled atmosphere applications. They are designed to be located in a pit in the floor. They load from the top. They can be electric or gas fired. Various kinds of elements systems are used for the electric versions. Each one is custom designed for an application. Specifications are per detailed quotation. Typical applications include carburizing, carbonitriding, and tempering of long shafts. Complete atmosphere control systems are available. Temperatures to 2200°F (1200°C) are available. Uniformity of +/-10°F (+/-5°C) is possible.


Processes


Markets

Specifications

Dimension
W
H
D
* All dimensions in inches unless otherwise specified.
Power
* All power values in KW unless otherwise specified.
Weight
* All weights in Lbs unless otherwise specified.


Additional Features

DOOR AND SEAL
The typical door seal is a wide pad of ceramic fiber. This seals against a rigid ceramic fiber board attached to the case. Controlled atmosphere furnaces can also feature sand seals. The most common door is a counterbalanced lift and swing door.
DIGITAL PID CONTROL SYSTEM
The standard control is a Honeywell UDC 2500 digital PID 3 mode tuning control with two displays. All fuses, transformers, contactors, and controls are located in a NEMA 12 panel with a panel mounted fused disconnect switch. Quiet, long life solid state power contactors are standard; SCR power controls are optional. The thermocouples are Type K. Thermocouple break protection is included. A Honeywell UDC 1200 digital FM approved high limit back up control with manual reset is included with back up contactors and separate thermocouple element. Limit switch shuts off furnace power if the door is opened. Control voltage is 120 volts. The control circuit and each power branch circuit are fully fused. A NEMA 13 lighted On/Off switch is included. Meets National Electrical Code.
TESTING AND INSTRUCTIONS
The furnace is power tested to insure proper watt ratings. The controls are fully calibrated and the control system completely tested. A complete instruction manual includes easy start up instructions, theory of operation, maintenance instructions, parts list, general dimension drawing, general assembly and subassembly drawings where required, and a detailed trouble shooting guide. A ladder logic diagram and panel layout are prepared on CAD for easy readability.
START UP SERVICE FOR ATMOSPHERE PANEL
L&L will check out and leak test the atmosphere system, inspect the customer’s assembly of the furnace, check tightness of elements, start up equipment, tune controller, adjust SCR, instruct customer’s personnel in how to do this, train operator in the use of the control systems, review the furnace manual, test for proper operation of all components and systems and start, watch and run the bakeout cycle. This typically takes 2 to 3 days. See link for details
START UP SERVICE
L&L will check out and leak test the atmosphere system, inspect the customer’s assembly of the furnace, check tightness of elements, start up equipment, tune controller, adjust SCR, instruct customer’s personnel in how to do this, train operator in the use of the control systems, review the furnace manual, test for proper operation of all components and systems and start, watch and run the bakeout cycle. This typically takes 2 to 3 days.
WARRANTY
The furnace is warranted for one year except for elements and thermocouples which are warranted for six months. See warranty sheet Q12W.
FANS
Most of these furnaces feature bottom mounted fans for recirculation of the furnace atmosphere. These are typically water cooled fans that mount as a plug unit. Recirculation baffles are typically used also.
304 OR 330 STAINLESS ATMOSPHERE RETORT WITH WATER COOLED COOLING ZONE
The work is pushed through a 304 stainless steel (or 330 alloy for optional 2000F unit) retort. This is one continuous 5” O.D. pipe from beginning of the heating zone to the end of the cooling zone. Each end has a sloping counterbalanced vertical door. A half-moon boat contains the load. A stainless steel water jacket with inlet and outlet pipe is welded around the outside of the cooling section. A regulating valve controls the water flow.
CERAMIC FIBER INSULATION FEATURES FAST HEAT UP AND COOL DOWN
The entire furnace, except for portions of the hearth, is insulated with ceramic fiber and mineral wool. The total insulation thickness is typically 8.” 2600F (1425C) fiber is used for 2200F (1200C) furnaces and 2300F (1260C) fiber is used for 2000F (1095C) or below. The bottom, where typically a fan is located, normally has castable refractory for erosion resistance. No asbestos is used.
TYPES OF HEAT SOURCES
Depending on the application, a wide variety of heat sources can be used. Gas fired units can be direct fired where atmosphere control is not important. Radiant tubes are used on gas fired units where atmosphere must be controlled. Electric furnaces can feature coiled, ribbon or rod type elements or can have elements enclosed in radiant tubes. Top to bottom zoning is possible with some types of elements.
HEAVY DUTY CASE
The case is typically made of strongly reinforced 3/16 thick steel. It is primed with 800F silicon paint and finished in machine enamel. Larger units are fabricated in more than one section for shipping purposes and erected on site.

Additional Options

CONTROL, RECORDER AND ELECTRICAL OPTIONS
CONTROL, RECORDER AND ELECTRICAL OPTIONS
JIC CONTROL OPTION
This includes a NEMA 12 control cabinet, all oil tight switches and a panel mounted fused disconnect switch. Zone switches if included are percentage timers.
MOTOR DRIVEN VENTURI SYSTEM
A motor driven venturi vent system is available. This system exhausts air out of the furnace and pulls in fresh air. Air inlets are located per customer specifications. (NOTE: venturis work by blowing air past a tube that is inserted into the furnace. This creates a vacuum without blowing cold air into the furnace. It has the advantage of having a controlled exhaust and minimizing heat shock in the furnace.) A 1 H.P. motor, complete with motor starter, drives the system. Capacity is 300, 600 or 1250 CFM, depending on the size of unit ordered. A stack should be installed to exhaust the hot air. Normally, a hand operated stainless steel damper is provided with the venturi system to control the amount of air being exhausted from the furnace.
PROGRAMMABLE MOTORIZED VENTURI
The venturi motor is controlled with a magnetic motor starter and push-button, with a relay programmed by the programmable temperature controller for turning the motor on and off in order to follow a programmed cooling curve. A separate pneumatically controlled inlet damper is normally also added. The inlet and out dampers then open or close with the programmed switch.
TWO TO EIGHT ZONE SCR POWER CONTROL WITH MANUAL BIASING
Digital biasing control is included to adjust relative output of SCRs to adjust temperature uniformity. There are up to 8 separate Zero Fired SCR power controls, one for each zone of heating. This allows you to fine tune the furnace for different temperature points. The SCRs are microprocessor based. The biasing switches have 99 increments.
TWO ZONE SCR POWER CONTROL WITH MANUAL BIASING
Digital biasing control is included to adjust relative output of SCRs to adjust temperature uniformity. There are 2 separate Zero Fired SCR power controls, one for each zone of heating. This allows you to fine tune the furnace for different temperature points. The SCRs are microprocessor based. The biasing switches have 99 increments.

Downloads

Brochure For PT