WMOD00479

• Title: Design and Field Testing of a Remote Ground-Based Liquid Propane Dispenser
• Weather Modification - Doc Type: Report

In addition, a tan." level sending unit was installed on
each tank and connected to an analog channel of the
microprocessor. This was an attempt to have further
independent documenw.tiorr that liquid proilane was
being released and to monitor propane reserves.

T\\"o dispensers of this new design were installed
on Haskell Peak (2,372 m) on Jan. 8, 1990. Two
dispensers were installed to check consistency between
the dispensers ar.d exercise the capaiJilities of the
Inicroprocessor ia ensuring that each tower could
cOillffillnicate ir.depender..tly. Fig. 6 S30WS t;i~ {\\:o
disper.sers operating aI this site. An hourly data
sun....."liary for one of these cispensers is shown in Fig.
as recorded by the PC in Sacramento. Seeding began at
4:15 a.m. PST and is indicated by the drop in
temperature for nozzle three (CH 08) and the increase
in flow rate shown in CH 02. One also sees the tank
level dropping (CH 04). It was found, however, that the
sending unit used for monitoring tank level was not
sensitive enough to reliably respond to small changes.
In fact, as much as a 190 L drop in liquid level was
required before the sending unit would chaIlge.

It can be seen in Fig. 7 that when the solenoids
were actuated, the temperature for the non-operating
nozzles would drop by 5 to 10~F since both the solenoids
and the temperature transducers are referenced to the
same battery. When battery voltage drops, it produces
an artifical temperature drop. This could orJy be

,-

Figuce 6 Two second-generation propane dispensers
operating on Haskell Peak Jan. 30, 1990. Note distinct
ice crystal plume moving downwind from dispensers.

corrected by having a different power supply for the
solenoids and the transducers. This is being corrected for
the coming winter's program. Fig. 8 is a closeup of a
nozzle after 14 hours of operation. One can see tbat ice
bas built up on top of the temperature arm and around
the outer edge of the nozzle, but the nozzle is still
spraying adequately. This would not be the case if
methanol had not been added to the propane. Note the
rime ice on the tower guy wires and antenna.

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Figuce 7 Printout of hourly data from one of two
stations operated on Haskell Peak on Jan. 30, 1990.
Nozzle 3 (CH 08) shows temperature in evaporating
plume of pro;>ane.