GB2165698A

GB2165698A - Fluid flow detector

Info

Publication number: GB2165698A
Application number: GB08525412A
Authority: GB
Inventors: Brian J Graves
Original assignee: Emhart Industries Inc
Current assignee: Emhart Industries Inc
Priority date: 1984-10-17
Filing date: 1985-10-15
Publication date: 1986-04-16
Also published as: GB8525412D0; FR2571846A1; AU4248385A; DE3519770A1; JPS6197527A

Abstract

In a fluid flow detector having a housing (12) which can be connected to an opening of a conduit (16) the corrosive effects of water, oil, or other fluids are substantially eliminated by providing a housing (12) of plastic e.g. fibre glass reinforced nylon. <IMAGE>

Description

SPECIFICATION Fluid flow detector The present invention pertains to a flow detecting mechanism and, more particularly, to a flow detecting mechanism useful for operating other mechanisms such as a switch.

Flow detecting mechanisms of the type referred to have many varied applications for sensing and controlling flow in fluid carrying apparatus as well as operating associated structure in response to the presence or absence of fluid flow. Many such mechanisms now available send fluid flow by movement of a vane or like detector disposed in a fluid carrying conduit. Physical movement of the detector is accomplished either directly by fluid flow impinging thereon or by use of structure such as orifices, blades or turbines in the conduit that creates a pressure differential which causes shifting of the detector. This physical movement must then be transmitted externally of the conduit to operate a switch, usually electrical, to indicate the presence of flow.

A typical example of such flow detecting mechanisms is that described in U.S.

4,454,768 issued June 19, 1984. As is typical of such devices described in this patent, the housing or saddle which carries the actuator means is fabricated of a metal such as aluminium or copper. While such devices have been for the most part satisfactory, they do have corrosion problems. More specifically, over a sustained period of time electrolysis takes place and corrosion of the saddle occurs. This is a particularly serious problem due to the tremendous fluid pressures which could be generated within the system. Such pressures could cause a catastrophic failure of the detecting mechanism.

Accordingly, it is a feature of the present invention to provide a flow detecting mechanism that resists the corrosive effects of the fluid being detected. The present invention relates to a mechanism for detecting flow in a fluid carrying conduit which, in general, comprises a saddle fabricated of plastic and adapted for securement to the conduit in overlying sealing relationship to an opening to the conduit, and flow detecting means adapted for insertion in the conduit and shiftable in response to fluid flow therethrough including a reactor member extending into the saddle. The mechanism is especially suitable for use with a conduit having an inside diameter of up to 3 inches (about 7.6 cm).

There now follows a detailed description to be read with reference to the accompanying drawings, of a flow detecting mechanism embodying the invention. It will be realised that this mechanism has been selected for description to illustrate the invention by way of example.

In the accompanying drawings: Figure 1 is a side view taken in section showing a flow detecting mechanism embodying the invention in combination with a conduit through which a fluid may flow; and Figure 2 is a view similar to Fig. 1 showing another side elevation of the mechanism in conjuction with a conduit.

Referring now to the drawings, there is shown a flow detecting mechanism (10) which is enclosed in a housing or saddle (12) that is adapted to be connected to an opening (14) of conduit (16) through seals (18) in a manner well known in the art. The saddle (12) is comprised of a cup-shaped member (20) having an opening end (22) and a base (24) having opening (26) therein. The opening (22) is closed by a resilient member (28) which forms a tight seal with the housing. A rigid plate (30) holds seal (28) and a backup plate (32) in place.

A flow detection means (34) responds to fluid flow in conduit (16). Detecting means (34) includes a reactor member (36) and an actuator means (38). Reactor member (36) includes a shaft (40) and a rigid arm (42) which is fixed to the shaft. Shaft (40) extends through apertures (44) of plate (30) and (46) of backup plate (32) and is held in a seal tight relation with resilient member (28). Shaft (40) is made to pivot about point (48) through the pivoting of the distal ends 42' and 42" engaging grooves in backup plate (32).

Actuator means (38) includes a paddle (50) that is carried to conduit (16) and is pivotally mounted on pin (52) through coil springs (54) and (56). More specifically, the distal ends 54' and 56' are connected to the paddle (50). The reactor member and the actuator means are pivotaliy connected together through the other ends 54" and 56" being connected to or engaged with a sleeve (58) carried on the arm (42) of the reactor member.

As shown, pin (52) is fixedly held in line with the opening (26) through cylindrical notches (27) and (29) to substantially prevent fluid flow from entering the housing.

Referring in particular to Fig. 2 with a fluid flow in the direction indicated by the arrow, paddle (50) is forced counterclockwise about the pin (52) which in turn pivots arm (42) and thus shaft (40) in a clockwise direction to close a switch (60). When fluid flow in conduit stops, there being no force acting on paddle (50), spring (62) causes shaft (48) to pivot counterclockwise to open the switch (60) and return the paddle (50) to its "at rest" position (64) through the coil springs (54) and (56). The fact that the actuator means and the reactor member both have a pivot point requires less force to open the switch (60).

In accordance with the present invention, saddle (12) is fabricated from plastic. The plastic must be able to withstand pressures in the order of 850 psi (about 5862 kN/m2) for conduits having an inside diameter of up to 3 inches (about 7.6 cm). Therefore, it must be very strong and tough. But more importantly, it must be substantially impervious to fluids such as water or oil for sustained periods of time (20-30 years). A plastic which has been found suitable is a fibre glass reinforced nylon marketed by Dupont under the lable Zytel 90G301. Such material was subjected to water at a temperature of about 187"F (about 86"C) and 175 psi (about 1207 kN/m2) for a period of 6 months by Underwriters laboratory. The material was found to be substantially impervious to the heated water.

Claims

1. A mechanism for detecting flow in a fluid carrying conduit comprising: (a) a saddle fabricated of plastic and adapted for securement to said conduit in overlying sealing relationship to an opening to said conduit, and (b) flow detecting means adapted for insertion in said conduit and shiftable in response to fluid flow therethrough including a reactor member extending into said saddle.

2. A mechanism according to claim 1 wherein said saddle is a nylon, glass reinforced plastic.

3. A mechanism according to claim 2 wherein said saddle is fabricated of Zytel 90G301.

4. A mechanism for detecting flow constructed, arranged and adapted to operate substantially as hereinbefore described with reference to the accompanying drawings.