Home Page >>> Backstage Area >> Laser Hobbyists > Hobby Archives - Hobbyist's Hazer

Hobbyist's Hazer

This page was contributed by Mark Schweter schweter@mail.bright.net

Introduction:

    This design was developed by experimental methods and should NOT be construed to be a final design, or, the BEST. (It does work in my basement AND it started hazing the upstairs too!).

    The haze stays suspended, at a usable level, for approximately an hour or so, after the unit is shut down. The heater element is switched separately so the fan can continue to run, thus cooling the unit after use.

Drawing 1

Drawing 2

    The heater element is a monolithic aluminium cast unit, [see photo below] as used in "Party-Perk" type coffee makers.

    The heater is filled to the mould mark on the inside, which is at the same height as the element winding, in the bulge, around the outside.

    Maximum temperature/haze output is achieved in approximately one hour of heating. This slow start-up is a side-effect of using the heater at 30V instead of it's designed 110V. In the current test-bed, the heater is enclosed and packed in fibber insulation, achieving approximately 525 F as opposed to 400 F when un-enclosed. The heater draw at 30V is approximately 1.5A.

Design Concerns:

A) Possible melting of the heater.
B) Possible ignition of the Mineral Oil.

A) The "Party-Perk" heater element is 110VAC. In it's intended use, however, it is designed to sink to ~3 Gallons of water. I *have* turned one of these on on, removed from a pot, and it DID MELT!!!!!!. This previous experience led to the use of the "ballast" transformer in the heater circuit. The 30V transformer will allow the heater to reach only 400-550 F, depending on the enclosure/insulation design.

B) The "flash point" of mineral Oil is 444 F, open cup test, per Sax's Dangerous Properties of Industrial Materials. This is the second criteria for limiting the heater's maximum temperature.
    A flashpoint is the temperature at which a substance will ignite IN THE PRESENCE OF AN IGNITION SOURCE. In the design, as currently operating, the mineral oil, IN THE HEATER, is at ~525 F to generate the "smoke". The same effect you get if you run a french-frier at too high a temperature.
    Immediately above the heater, in the generating chamber, the air drawn through the end-cap vent cools the smoke/air combination to ~80 F, well below the flash-point of mineral oil (by thermocouple measurement in a 68 F room).

    The 12in. extension to the hazer's output helps "collimate" the flow and increases the dispersion speed into the room. The gap between the heater housing and the fan, [see picture] allows additional air to be drawn through the fan and keep full air velocity out the hazer's mouth. This suction design was used because in the bench top trials airflow over the un-enclosed heater, in sufficient velocity for dispersion, cooled the unit below 300oF severely curtailing haze production.

Known Problems:

A) Current design does not have fuses, etc.
B) Slow start-up.
C) The high volume of haze/mist exiting the generator has a tendency to condense inside the housing and on the fan.
D) Using unknown Molecular Weight mineral oil , after approximately half the volume of mineral oil evaporates, the polymerised higher weight fluid begins to give off an offensive acrid odour - Keeping the fluid topped of with fresh oil seemed to cure this.

Future Trials/Modifications:

• Try adding a "jumpstart" momentary boost switch to the heater.

• Since sufficient heat is generated now that the heater is enclosed and insulated, test to see if returning to the original blowing fan design can be accomplished.

• Add a "Dial-a-WATT" control (wall dimmer?) to heater transformer input to allow control of heater temperature when full output is not needed, i.e., smaller venues.

Credits:

Original concept and surplus heater location: O.Steven Roberts
Fabrication/Testing: Mark Schweter

Most of the information and ideas in the Hobby Archives have been contributed by hobbyists and experimenters. If you have any comments or ideas to share, please contact us by E-mail.

DISCLAIMER: Some of the information in the Backstage area is provided by the persons or companies named on the relevant page(s). Laser F/X does NOT endorse or recommend any products/services and is NOT responsible for the technical accuracy of the information provided.  We provide this information as a service to laserists using the Backstage area. 

[ Introduction | Hobby Archives | Hobby FAQ | Laser Construction ]