vb Db ea. 3.1.4 Environmental Requirements The site where the equipment was to be used made it necessary that the equipment operate . in a warm and humid climate, Also, the instruments had to be capable of operation when out on the water and be unaffected by wave action. Tests were made on the resistance that materials offered to corrosion, as wellasthe mechanical functioning of the instrument under adverse ton jee RGAERA SOIRARLENEOIFAMIE RE eTay ay yreeear A ER EAE TMROO conditions. 3.2 TOTAL FALL-OUT COLLECTOR The total fall-out collector consisted of a 1-gal polyethylene bottle and a 6-in. funnel con- nected to it by tygon tubing (Fig. 3.1). Polyethylene and tygon were used because of their chemical inertness; also, the polyethylene bottles could be dropped without breaking. The total fall-out collector was considered a safety measure to ensure a collection of fall- out in case other instrumentsfailed. ~eF 3.3 DIFFERENTIAL FALL-OUT COLLECTOR: ; a The differential fall-out collector was designed to collet solid fall-out particles asa function of time. The unit consisted of a lucite tray dividedinto 72 compagmigents, a varnished Fiberglas slotted belt that was pulled over the tray exposing each comp sent individually, a 6-volt Magnatorc motorto pull the belt, a battery for the. sourceof power, and a trigger mechanism for starting the motor (Fig. 3.2). Two collecting rates were used; one, at the nearer stations, had approximately 2-min collecting increments, and the other, at the more distant stations, had approximately 6-min collecting increments, . In addition, provision was made to remove the lucite tray,putit in a. wooden box, and seal off the compartments by meansof a lid that was surfaced onttié side with-a soft piece of rubber. This lid was then banded to the box, making a wateetight seal. This box was used for shipping. = Trigger Mechanism. The¢ifferential fall-out collector was started at shot time by a trigger mechanism. This mechanism consisted of two light-sensitive circuits: a light-level circuit or phototube circuit and a:light-level differential or photocell circuit. Either circuit would trigger the differential fall-out collector,-and both circuits had 360° vision (Fig. 3.3), which was essential since theseunits were used on rafts in the lagoon. Both circuits were adjustable for sensitivity so that thefactor of distance from the shet island could be taken into account. The circuit diagram of the trigger mechanism is.given.in Appendix C. 3.4 ipos- INCREMENTAL LIQUID FALL-OUT COLLECTORS These units were designed primarily to collect liquid samples as a function of time. Each consisted of a vertical lucite column divided into sections separated from each otherby a ball- float valve (Fig. 3.4). Each section held 0.15 in. of rain. Recording rain gages were used in conjunction with the incremental collectors to determine time of arrival. 3.5 with- gure her- le- RAIN GAGE The recording rain and snow gage manufactured by The Instruments Corp. was used to measurethe rate of arrival of liquid fall-out at two recording rates, One instrument made a 7-day trace, and the other made a 3,5-day trace. This instrument is used by the United States Weather Bureau (Fig. 3.5). ent 19 ne