Elephant trunks

Install local air exhaust pickup points at filter (e.g., elephant trunks)... 

Other types of local ventilation methods include elephant trunks and free-hanging canopies and plenums. The elephant trunk is simply a flexible vent duct that is positioned near a source of contaminant. It is most frequently used for loading and unloading toxic materials from drums and vessels. Free-hanging canopies and plenums can be either fixed in position or attached to a flexible duct to enable movement. These methods will most likely expose workers to toxicants, but in diluted amounts. 

A 6-in-diameter elephant trunk is used to remove contaminants near the open bung of a drum during a filling operation. The air velocity required at the end of the elephant trunk is 100 ft/min. Compute the volumetric flow rate of air required. 

All potential solvent exposure points will be in close proximity to elephant-trunk exhaust ducts for ventilation. 

Washed solvent system The washed solvent tank is a grounded 55-gal drum. An elephant trunk positioned over the bung vents the drum to the exhaust system. Material fed to the drum is cooled from the POD operating temperature of approximately 190°F to 80°-110°F by a stainless steel heat exchanger. 

If necessary, solvent and emulsion tanks are vented to elephant trunks and into the exhaust system through valves V2a and V2b. 

Solvent collection device with ability to vent to a laboratory hood or elephant trunk. 

Table 1. Possible function and description of elephant trunk behaviors related to chemical signal reception.

The capture velocity is approximately 8.5% of the face velocity at a distance equal to the diamete of the local exhaust opening. Thus, a 3-inch-diameter snorkel or elephant trunk having a face velocity of 150 fpm will have a capture velocity of only 1 fpm at a distance of 3 inches from the opening. Because the air movement velocity is typically at least 20 fpm, capture of vapors emitted at 3 inches from the snorkel will be incomplete. However, vapors emitted at distances of 2 inches or less from the snorkel opening may be captured conpletely under these conditions. 

Use of local exhaust ventilation ( e.g. "elephant trunks", slotted exhaust hoods, and canopy hoods). 

Within the field of robotics, different natural manipulators such as elephant trunks, octopus arms, squid tentacles and snakes have been considered as models for the development of high-performance (means of locomotion or grasping) robotic devices. 

Local exhaust systems consist of such devices as bench slots, canopy hoods, elephant trunks, back draft benches, and laboratory fume hoods. It is the standard fume hood that is the focus of discussion in this section. 

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