Sybron Corporation

Thermolyne Holdings Inc.

William J Walsh

Roger W Earle

A triac and a mechanical relay, in series with the electrical heater of an incubator, together switch heater current on and off at the same set point temperature if the triac fails short. Similarly, a second mechanical relay in parallel with the triac switches heater current around the triac, should the triac fail open.

Failure protection in temperature control

An electrically-heated dry bath wherein a metal block having receptacles for receiving test tubes or the like has resistor heaters fixed thereto and a thermistor temperature sensor therein. A control circuit is provided which connects and disconnects electrical current to and from said heaters in response to the temperature sensor. The control current is fedback such as to eliminate a factor J(S) from the overall transfer function of the circuit, J(S) being a transfer function expressing how various thermal time constants in the bath would, unless neutralized, make the effective time constant of the controlled system deviate from the ideal on-off transfer function.

Dry bath temperature control

A furnace having an easily disassembled vacuum chamber to facilitate muffle replacement. The muffle is located over pins on the vacuum chamber base and is held against the base by a leaf spring between the muffle and the vacuum chamber top. The cylindrical wall of the vacuum chamber is correctly located with respect to the muffle by upright spacer bars upstanding from the vacuum chamber base about the periphery of the cylindrical wall. The spacer bars further serve to tie the top and base of the vacuum chamber together and against the cylindrical wall. The furnace is bottom loaded and has a door seal carried by the base so that the seal is not exposed to the direct heat from the muffle when the door is opened.

Vacuum firing porcelain furnace

A kiln has a bottom opening for loading the objects to be fired into the firing chamber. The door for closing the firing chamber provides the hearth of the kiln and supports the objects to be fired. A parallel linkage mechanism maintains the door in a horizontal orientation as it is moved from the closed position wherein the objects to be fired are in the kiln, to the open position wherein the objects are supported in front of the kiln.

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Dubuque, IA, United States of America

William J Walsh