GB2134011A

GB2134011A - Sewage distributor nozzles

Info

Publication number: GB2134011A
Application number: GB08402035A
Authority: GB
Inventors: Brian Dennis Nicks
Original assignee: Tuke & Bell Ltd
Current assignee: Tuke & Bell Ltd
Priority date: 1983-01-26
Filing date: 1984-01-26
Publication date: 1984-08-08
Also published as: GB2134011B; GB8402035D0

Abstract

Nozzles for arms of rotary distributors or other distributor ducts for filter beds or other effluent purification apparatus are formed from elastomeric material as a one piece moulding comprising a body defining a through jet passage (11) typically convergent in the downstream direction and two external radially projecting flanges (14, 15) defining a groove to receive the edge of the duct opening in which the nozzle is mounted, the flexible or resilient material enabling ready insertion or removal of the nozzle and effective sealing of the edge of the duct opening. <IMAGE>

Description

SPECIFICATION Sewage distributor nozzles This invention relates to spray or jet nozzles for use with the distributor ducts of apparatus for biological filtration or otherwise purifying liquid sewage or other liquid effluent, particularly but not exclusively nozzles for the arms of self-acting or power-driven rotary or other distributors used with biological filtration systems or for liquid distribution over filter media.

Various forms of nozzles and means of mounting these in the associated apertures of the arm or other duct are known, past practice has been to form the nozzles from rigid corrosion resistant materials such as gun metal or hard plastics. These may be inserted in the apertures by substantial pressure coupled with the use of an expanding tool in the case of one piece metal nozzles, or by use of further components such as screw fittings, bushes, sealing glands and the like.

This makes the nozzles costly and time consuming to fit, service or replace, particularly under operating conditions. It is desirable that the nozzle protects the edge of the duct aperture from exposure to corrosion by the action of the effluent so that a close fluid-tight seal is desirable.

The object of the invention is the provision of a simple and readily replaceable nozzle which is durable, efficient in performance, easily serviced and replaced, and economical to produce.

According to the invention there is provided a nozzle for a distributor duct form from flexible or resilient material to include an open ended hollow body defining a through passage and having longitudinally spaced laterally projecting locating abutments, the body being opperatively inserted in an opening in the duct side wall by being resiliently deformed so as to seat the edge of said opening securely between the abutments with one said abutment within the duct.

Conveniently the abutments are a pair of external continuous or discontinuous flanges of the body opposing radial faces of which define a groove in which said edge seats in use; and the nozzle is a single integral moulding of an elastomeric material whose resilience facilitates said insertion or subsequent removal and ensures adequate fluid-tight sealing of the edge of the duct side wall opening.

One example of the invention is now more particularly described with reference to the accompanying drawings wherein: Figure 1 is a longitudinal vertical section of a nozzle fitted in a distributor duct, Figure 2 is an end elevation of a modified form of inner flange of the nozzle, and Figure 3 is an end elevation of another modified form of inner flange.

Referring firstly to Figure 1, a rotary distributor for a filter bed has a plurality of tubular distributor arms 9 (a portion of one only shown) extending radially from a rotating centre assembly of known construction (not shown) from which sewage or other liquid effluent is fed into the arms for distribution through a series of nozzles 10 (one only shown) in a side wall of each arm 9.

Nozzle 10 is a one-piece moulding of an elastomeric plastics material, for example a nitrile composition of about 90 Shore. The material is highly resistant to attack from sewage effluent or other waste products, weathering, or impact damage, is compatible with ducts made from any material, and will conform readily to any irregularity in the side wall )pening. It is sufficiently resilient to allow easy fitting and removal without tools while providing a good sealing fit in the opening. The material can be moulded to close tolerances and a high finish so that the dimensions and performance characteristics of the nozzle are accurately predetermined and costly machining and finishing, as required for metal nozzles, is avoided.

Nozzle 10 is a generally conical hollow body defining a through passage 11 which, in this example has a short parallel maximum diameter bore 12 at its upstream end and then converges to its downstream end to provide a tapered jet passage section 13. The upstream end portion of the nozzle which defines the parallel bore 12 is provided with two external radially projecting axially spaced outer and inner flanges 14, 1 5 defining a groove 16 dimensioned to fit tightly onto the edge of the duct opening, inner flange 1 5 being inside the tubular arm on assembly.

For some applications an internal rim 17 at the upstream mouth of bore 12 may be chamfered or rounded to improve the flow characteristics.

A set of nozzles providing a range of alternative sizing of passage 11 may be provided for fitting in a standard size of arm side wall opening, e.g. by forming each nozzle of the set to a standard axial length and diameter of the upstream end portion but varying the angle of convergence of the tapered section 13, for example alternative nozzles for fitting in a 318 mm (1+") opening could have minimum passage diameters ranging from 11 mm (7/16") to 20.5 mm (13/16") in increments of 1.5 mm (1/16"). Similarly graded sets of nozzles each to fit one of a range of sizes of openings, e.g. for opening diameters from 24 mm (15/16") to 38 mm (12") give an overall range of passage sizes (minimum diameter in each case) of from 6 mm (+") up to 22 mm (7/8").

The nozzles are light in weight and very easily fitted and removable as they can be deformed by squeezing under finger pressure to insert or free the inner flange 1 5 into or from the opening. It is believed that they may be less subject to clogging than rigid nozzles and if obstruction does occur clearance may be possible by squeezing or deforming the free end of the nozzle to release the obstruction without having to remove the nozzle.

The ease of interchange means that the performance of the distributor can be adjusted under operating conditions by substituting different sizes of nozzles and/or averaging a mix of sizes along the length of the arms.

The above shaping and proportions of the passage 11 as shown in the drawings are selected to improve the coefficient of discharge (Cd factor) of the nozzle for greater operational efficiency. The Cd factor is the relationship of the actual discharge QA from the nozzle to the theoretical discharge (OT), the most efficient possible performance being when Cd=1, i.e.

QA =Cd QT The theoretical discharge is calculated as follows:

where D=diameter of discharge from nozzle g=gravitational constant H=head of inflow to nozzle The actual discharge QA has to be established by flow testing the nozzle under controlled conditions e.g. by measuring the weight of water passed in a given time.

It has been found that the form of nozzle shown in the drawing or one having those proportions in smaller or larger sizes gives a Cd factor approaching 1, i.e. has excellent efficiency of performance. This is particularly important in the form of distributor in which the rotation of the arms is provided by the reaction of the jets of liquid issuing from the arm nozzles.

In order to facilitate insertion and removal of the inner flange 15 while maintaining or enhancing secure retention of the nozzle in the opening said flange may be non-circular, discontinuous and/or be shaped to provide one or more notches or minimum radius portions to give a "lead in" or bayonet fastening effect for assisting its engagement and insertion into or withdrawal from the side wall opening of arm 9.

One such arrangement is shown in Figure 2 where inner flange 1 5a is near oval with the minor diameter vertical in use and equal to the diameter of the outer flange 14. This arrangement also has the advantage of streamlining the profile of flange 1 5 in the direction of flow along the duct defined by arm 9. The major diameter (horizontal in use) of this form of inner flange is substantially greater than the diameter of outer flange 14 but in some constructions the major diameter may be substantially equal to that of the outer flange and the minor diameter may be less e.g. approaching the diameter of the side wall opening.

Another modified form of inner flange 1 sub is shown in Figure 3, here said flange is circular and its diameter may be equal to or greater than that of the outer flange. To facilitate insertion and removal the inner flange is provided with a cutout or notch 20.

While the convergent tapered nozzle shown in the drawings is preferred other shapes and profiles of nozzle incorporating the invention may be used for some applications. Thus the external profile need not correspond to the internal profile, e.g. the thickness of the walls defining passage section 13 may be non-uniform in the axial direction. The nozzle through passage may be parallel in axial section or divergent in the direction of flow instead of convergent. The crosssection of the nozzle passage may be square, rectangular or otherwise non-circular.

Claims

1. A nozzle for a distributor duct formed from flexible or resilient material to include an open ended hollow body defining a through passage and having longitudinally spaced laterally projecting locating abutments, the body being operatively inserted in an opening in the duct side wall by being resiliently deformed so as to seat the edge of said opening securely between the abutments with one said abutment within the duct.

2. A nozzle as in Claim 1 wherein the abutments are a pair of external flanges of the body, opposing radial faces of which define a groove in which the edge of said opening seats in use.

3. A nozzle as in Claim 1 or 2 formed as a single integral moulding of an elastomeric material.

4. A nozzle as in Claim 3 in which said material is a nitrile composition of about 90 Shore.

5. A nozzle as in any preceding claim having a body defining a tapered jet passage converging to its downstream end.

6. A nozzle as in any preceding claim in which said one abutment for operatively positioning within the duct is a non-circular or discontinuous flange.

7. A nozzle as in Claim 6 wherein said one abutment is a substantially oval flange.

8. A nozzle as in Claim 6 wherein said one abutment is a flange having a cut-out or notch to facilitate insertion and removal of the nozzle from the duct.

9. The combination of a nozzle as in any preceding claim and a distributor duct for a filtration system.

10. The combination as in Claim 9 in which said duct is an arm of a rotary distributor.

11. A nozzle for a distributor duct substantially as hereinbefore described with reference to and as shown in Figure 1, or Figure 1 as modified by Figure 2 or 3, of the accompanying drawings.

12. A distributor duct assembly substantially as hereinbefore described with reference to and as shown in Figures 1, or Figure 1 as modified by Figure 2 or 3, of the accompanying drawings.