Bacharach Tru Pointe Spécifications télécharger pdf (Page 19)

Tru Pointe® 2100 Instruction 0028-9003

6 Principle of Operation

The principle of operation of the Tru Pointe

2100 is based on the turbulent ﬂ ow of ﬂ uids and

gasses. Turbulent ﬂ ow has a high content of ultrasound, which the Tru Pointe

2100 can detect.

Imagine air leaking from a tire. Because this is such a large leak, your ear can detect this sound,

however your ear hears only about 1/3 of the actual spectrum of sound which exists. The sound

of small leaks is mostly ultrasonic which your ear can not detect.

EXAMPLE: A piece of straight tubing connected to a

gas supply and left free to exhaust into the atmosphere

will not generate sound if the volume of gas through

it is such that turbulence does not take place. Yet for

that same ﬂ ow, an opening as small as 0.005 of an inch

could generate enough sound to be heard several feet

away.

For a leak to happen there must be an opening in the system that carries a gas or ﬂ uid. Normally,

these openings are not clean smooth holes, but passages through cracks with many jagged

edges and internal chambers. Fluid or gas escaping through an “oriﬁ ce” like this, is forced into

turbulence, random circular-like motions. Inside a tube where a gas may be ﬂ owing, the ﬂ ow is

normally laminar which means that a given layer of gas does not mix with layers above it or below

it. This condition happens in a straight long tube when the velocity of the ﬂ uid is not high. A gas

leaking out of a straight and long tube will not generate as much sound as if it were leaking out of

a small crack because the ﬂ ow is not turbulent.

The intensity of sound generated at a leak is a very complex function of the viscosity, the tem-

perature, the speed the ﬂ uid is moving, the Reynolds number, the pressure differential across the

leak, and the physical dimensions and characteristics of the oriﬁ ce. This is why it is impossible to

quantify the size of a leak with ultrasonic technology. A smaller leak may generate more sound

than a larger one.

The Tru Pointe

2100 detects ultrasound NOT the presence of a speciﬁ c gas. It is NOT a gas

“Sniffer”. Because of this fact, the Tru Pointe

2100 can function in areas where heavy wind or a

concentration of fumes renders other detectors useless.

WARNING! Ultrasonic detectors will not indicate a

leak if there is no turbulent ﬂ ow producing sound when

checked. If you suspect a toxic gas, natural gas, or

other combustible gas leak and it is not detected by the

Tru Pointe

2100, do not assume it doesn’t exist, and

use another method as veriﬁ cation there is no gas leak

present.

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Bacharach Tru Pointe Spécifications Page 19