CN105987207B - Micro- resistance pressure reduction type backflow preventer - Google Patents

Abstract

The invention discloses a kind of micro- resistance pressure reduction type backflow preventer, enters Water Check Valve and go out Water Check Valve to be arranged horizontally in the intermediate cavity between valve body and bonnet, its axis is consistent with valve body intake-outlet axis；Draining valve is arranged on below valve body, the axis that its axis is imported and exported with valve body intersects vertically, there are some osculums one to be connected with drain chamber under valve body on quartered, water-in and water-out check-valves is each provided with permanent magnet and armature, draining valve is provided with diaphragm, the outward flange of the diaphragm is pressed between valve body lower portion and bottom flange, is additionally provided with the through hole that intake pressure is introduced to diaphragm cavity of resorption, and valve body lower end is provided with the water trap function detection device that can connect the upper and lower chamber of diaphragm with bottom flange connecting portion.This invention takes a variety of aggregate measures for advantageously reducing flow resistance, flow resistance loss can be greatly lowered, and have reliable anti-backflow performance.

Description

Micro- resistance pressure reduction type backflow preventer

Technical field

The present invention relates to a kind of valve, more particularly to a kind of pressure reduction type backflow preventer.

Background technology

Backflow preventer, also known as dirty stream isolating valve, it is that one kind pollutes when strictly preventing Drinking Water pipeline from flowing back The safety features at water source, it can also be applied to other pipe-line systems for not allowing medium to flow backwards.

Backflow preventer pattern is more, and pressure reduction type backflow preventer is connect by industry due to function admirable, safe By, and promoted.Its typical construction represents in Chinese patent notification number CN201547347C, is stopped by clack box, water inlet Return valve, go out Water Check Valve and draining valve composition.But find in use, this kind of construction has the following disadvantages：

1. drag losses during flow of media is larger, main cause is to make draining valve reliably close, it is necessary to is made into water The opening pressure of check-valves is more than the closing presure (closing presure >=0.014MPa of national regulations draining valve) of draining valve, so The opening pressure of inlet check valve must be designed to larger (national regulations inlet check valve opens pressure >=0.02MPa)；Secondly, To make outlet check valve seal reliable, opening pressure should not be too small (national regulations go out Water Check Valve and open pressure >=0.007Ma)； Moreover area of passage in valve pocket everywhere and runner design are unreasonable, also up and down through there is one in the valve pocket of above-mentioned patent The valve rod of draining valve, cause local resistance loss bigger.After tested, under conditions of the design of each spring meets national standard, medium is worked as When flow velocity is 3m/s, for flow resistance loss up to 0.07~0.10MPa, this not only causes a large amount of energy consumptions, and relatively low in water supply pressure (such as 0.16MPa) area can not use at all.

In order to reduce flow resistance, applicant once have developed new a backflow preventer, Chinese patent notification number CN204164434, permanent magnet and armature are provided with water-in and water-out check-valves, partial spring is counteracted after valve opening Power；And drain valve structure is changed, eliminates the montant among valve pocket.After tested, when velocity of medium is 3m/s, flow resistance damage Failed to keep an appointment 0.4MPa, has and declines to a great extent, and water supply department is proposed to be obtained more in the relatively low area of pressure of supply water while certainly It is extensive to promote, it would be desirable to further to reduce.

2. draining valve is the critical component in backflow preventer, it is desirable to is reached in intake pressure P1 and middle cavity pressure P2 pressure differences During to setting value (national regulations 0.014MPa), draining can be promptly opened, because higher than middle cavity pressure in intake pressure When just carry out draining, therefore can definitely prevent medium flow backwards occur.In recent years, the various structures of draining valve continuously emerge, but put into practice Prove, some because spring force can not be adjusted, cause when use with the passing of time elastic force diminishes after, cause discharge pressure reduction, to security Bring hidden danger；Some causes sealing force inadequate, causes leak because of diaphragm size, spring force and port size three's mismate； Some because in runner some position flow section areas it is smaller, cause displacement small；Some can not because of the dirt deposited in valve pocket Easily cleaning in time, causes the kinematic pairs such as guiding valve and valve pocket to be consolidated by dirt, causes draining valve to open；More have Notably, in use for some time, drain function is completely lost.

3. there is no water trap function detection device, because water trap is made up of some parts, occurred unavoidably long afterwards using day Failure, such as spring rate reduce or fracture, guiding valve or valve rod kinematic pair are consolidated by dirt, flap and seal (material one For rubber) adhesion etc. occurs, when these failures occur unknown in use, are just carried out once sewage occurs and flows backwards Dissembling inspection, there occurs large amount of sewage refluence for one.

The content of the invention

The present invention is that a kind of micro- resistance pressure-reducing designed to solve the above-mentioned technical deficiency of backflow preventer flows backwards Preventer.

The above-mentioned technical problem of the present invention is mainly what is be addressed by following technical proposals：

A kind of micro- resistance pressure reduction type backflow preventer, there is valve body, bonnet, enter Water Check Valve, go out Water Check Valve and draining Valve；

Enter Water Check Valve and go out Water Check Valve to be arranged horizontally in the intermediate cavity between valve body and bonnet, its axis and valve Body intake-outlet axis is consistent；

Draining valve is arranged between valve body lower end face and bottom flange, and the axis that its axis is imported and exported with valve body intersects vertically, There are some osculums one to be connected with drain chamber under valve body on quartered；

It is characterized in that：It is described to enter Water Check Valve and to go out Water Check Valve and be each provided with permanent magnet and armature, also using upper There is the circlip of opening side, to facilitate dismounting to overhaul；

The draining valve is provided with the guiding valve being connected with diaphragm, and piston, the center of piston are equipped with the endoporus of guiding valve Axle upper surface under the action of the spring, contacts with the boss lower surface of pressing plate all the time；

Valve body lower end is provided with the water trap function detection device that can connect the upper and lower chamber of diaphragm with bottom flange connecting portion.

Technical scheme can also be further perfect：

Preferably, the bottom flange includes casting, there are the Round cylinders, in position of sinking at integral lower flange, middle part On some projections, the projection includes projection one and projection two；Close-fitting has sleeve in bottom flange Round cylinder endoporus, sleeve Guiding valve is equipped with endoporus, piston is equipped with the endoporus of guiding valve, the upper internal shoulder by guiding valve top of piston positions；Lower valve Cover the through hole for being additionally provided with and intake pressure being introduced to diaphragm cavity of resorption.

Preferably, cylindrical get on the bus in the upper end of the guiding valve has screw thread, the inner ring of diaphragm passes through clamp nut and packing ring pressure Tightly outside guiding valve on the upper surface of convex shoulder, in the case of not water flowing, the outward flange of diaphragm and inner ring are located substantially on same water In plane.

Preferably, the top of the guiding valve is provided with annular sword side, draining is formed with the sealing gasket installed in body base The valve port of valve, the Assurance of Size of valve port is in the case of normal water supply, the ratio pressure about 0.6MPa of the two, to ensure the reliable of sealing Property.

Preferably, the piston is made up of the piston ring outside central shaft, central shaft and two straight dowels, There are two mounting holes between muscle, the upper surface of central shaft contacts with the boss lower surface of pressing plate all the time under the action of the spring.

Preferably, the lower end of the piston is provided with spring, spring force can be by the regulation spiral shell with osculum two below Set regulation.

Preferably, the through hole that the intake pressure introduces diaphragm cavity of resorption is：It is drilled with the outer peripheral face of bottom flange projection one The radial direction small through hole one connected with diaphragm cavity of resorption, outer end is blocked with steel ball after brill；Bottom flange bottom surface is drilled with aperture one, with radial direction Small through hole one intersects vertically, and the aperture two with being connected positioned at valve body lower end face with intake antrum is on same center line；Pass through valve The inclined hole connected on body with intake antrum, corresponding through hole and aperture one, radial direction small through hole one on aperture two, diaphragm, will intake Pressure is incorporated into the cavity of resorption of diaphragm.

Preferably, there is boss the lower flange upper surface of bottom flange, boss is provided with and can easily exclude to accumulate in diaphragm The blowdown bolt of dirt in cavity of resorption.

Preferably, water trap function detection device is arranged on the projection two of bottom flange and valve body lower end face clamps diaphragm portion In the intercommunicating pore of position, including valve rod, O-ring seals three and fastening screw nut；The valve rod is stairstepping, and epimere is thinner, and top adds Work has frustum, and stage casing is used as guiding during its up and down motion, and prevents medium from leaking with O-ring seals three, and hypomere is machined with outer There is fastening screw nut 26 screw thread, end to prevent valve rod from loosening after valve port is shut.

Preferably, described intercommunicating pore includes the appropriate location of valve body lower end outer peripheral face and the outer peripheral face of bottom flange projection two Upper to be drilled with radial direction small through hole two and radial direction small through hole three respectively, outer end is blocked with steel ball after brill, and the axis of holes hangs down same In straight plane；Aperture three is drilled with the lower surface of valve body, is intersected vertically with radial direction small through hole two, the end of aperture three be machined with The conical surface that valve stem end frustum coordinates, the two composition valve port；The hole coordinated with valve rod is machined with the end face of bottom flange projection two, The hole intersects vertically with radial direction small through hole three, is communicated with aperture three and concentric, diaphragm outward flange is provided with corresponding aperture, with hole With one heart, the internal thread coordinated with valve rod external screw thread is machined with the downside of hole.

Beneficial effects of the present invention：

1st, take：Permanent magnet and armature are provided with two check-valves, so when valve port is fully open, can be supported The spring pressure for the nearly half of disappearing；Change drain valve structure, there is no through upper and lower montant in intermediate cavity；Medium is in valve pocket During flowing, each flow section area is spacious, and it is all with the contact site of each part or leave position, have 30 ° on part ~60 ° of chamferings or fillet, to reduce the aggregate measures that local eddy currents loss etc. advantageously reduces flow resistance.Surveyed through model machine, work as Jie When mass flow speed is 3m/s, flow resistance loss about 0.32MPa；Flow resistance loss about 0.025MPa, it has been water supply department when flow velocity is 2m/s Accreditation, available for the relatively low area of pressure of supply water.

2nd, the spring force of draining valve can accurately be adjusted to the discharge pressure of Standard, and anti-backflow is safe, and close Envelope property is good, and drainability is big, reliable operation；

3rd, whether structure of the detecting device function that is simple, easy to detect, can detecting draining valve at any time is normal, to send out in time Existing problem is repaired or replaced.

Brief description of the drawings

Accompanying drawing 1 is a kind of structural representation of the present invention；

Accompanying drawing 2 is drain valve structure enlarged drawing in Fig. 1；

Accompanying drawing 3 is water trap function amplification figure in Fig. 1；

Description of reference numerals：

1st, valve body, 2, bonnet, 3, enter Water Check Valve, 4, go out Water Check Valve, 5, draining valve, 6, circlip, 7, ball valve, 8th, O-ring seals one, 9, steel ball, 10, diaphragm, 11, bottom flange, 12, sleeve, 13, spring, 14, O-ring seals two, 15, regulation Swivel nut, 16, guiding valve, 17, piston, 18, blowdown bolt, 19, clamp nut, 20, packing ring, 21, pressing plate, 22, sealing gasket, 23, valve Bar, 24, O-ring seals three, 25, fastening screw nut；

A, inclined hole, b, aperture two, c, aperture one, d, radial direction small through hole one, e, osculum one, f, mounting hole, g, osculum Two, h, radial direction small through hole two, j, radial direction small through hole three, m, hole, L, aperture three,；

D1, projection one, D2, projection two, H1, intake antrum, H2, intermediate cavity, H3, water chamber, H4, drain chamber, P1, influent pressure Power, P2, middle cavity pressure, P3, discharge pressure.

Embodiment

Below by embodiment, and with reference to accompanying drawing, technical scheme is described in further detail.

Embodiment：

Micro- resistance pressure reduction type backflow preventer as shown in Figure 1, there is valve body 1, bonnet, 2, enter Water Check Valve 3, water outlet Check-valves 4 and draining valve 5, enter Water Check Valve 3 and go out the intermediate cavity that Water Check Valve 4 is arranged horizontally between valve body 1 and bonnet, 2 In H2, its axis is consistent with valve body intake-outlet axis, and draining valve 5 is arranged between valve body lower end face and bottom flange 11, its axle The axis that line is imported and exported with valve body intersects vertically, and has some e of osculum one to be connected with drain chamber H4 on 1 time quartered of valve body, enters Water Check Valve 3 and go out Water Check Valve 4 and be each provided with permanent magnet and armature, and use top to have the circlip 6 of opening, to it Rapidly assembled and disassembled, complete machine need not be unloaded from pipeline during maintenance, need to only pull down bonnet, 2, take out water-in and water-out non-return Valve 3,4 is just；Three ball valves 7 of the top of valve body 1 and bonnet, 2 are respectively in measurement intake antrum H1, intermediate cavity H2 and going out Pressure gauge is connected during water cavity H3 hydraulic pressure；Valve body lower end is provided with the row that can connect the upper and lower chamber of diaphragm with the connecting portion of bottom flange 11 Hydrophone function detection device；There is boss the lower flange upper surface of bottom flange, and boss is provided with and can easily exclude to accumulate in diaphragm Dirt in cavity of resorption, the blowdown bolt 18 for preventing guiding valve 16 and sleeve 12 from being consolidated by dirt.

The part-structure of the present invention is elaborated below：

Draining valve (as shown in Figure 2)

Draining valve is by O-ring seals 1, steel ball 9, diaphragm 10, bottom flange 11, sleeve 12, spring 13, O-ring seals two 14th, Adjusting bolt Adjusting screw 15, guiding valve 16, piston 17, blowdown bolt 18, clamp nut 19, packing ring 20, pressing plate 21, sealing gasket 22 etc. zero Part forms.Bottom flange 11 by lower flange, cylinder and in position on two D1 of projection one, the D2 of projection two form, four pour Cast solid, inner surface are stepped through hole, and sleeve is slightly prominent at connection plane；Bottom flange 11 is fixed by some screws On the lower surface of valve body 1, the outward flange of diaphragm 10 is pressed in therebetween；It is drilled with the D1 of projection one outer peripheral face radially small Through hole d, outer end is blocked with steel ball 9 after brill, bottom surface is drilled with the c of aperture one, is intersected vertically with the d of radial direction small through hole one, and with valve body 1 On the b of aperture two on same center line；By the inclined hole a on valve body 1, corresponding aperture and aperture on the b of aperture two, diaphragm 10 One c, the d of radial direction small through hole one, intake pressure P1 are incorporated into the cavity of resorption of diaphragm 10, and O-ring seals 1 are used to prevent outside medium Let out；The D2 of projection two is provided with water trap function detection device；The boss of lower flange upper surface is provided with a blowdown bolt 18, energy Easily pull down, the dirt for excluding to accumulate in the cavity of resorption of diaphragm 10 using the press water in valve, with antiskid valve 16 and sleeve 12 It is consolidated by dirt；Press-fitting has the sleeve 12 of stainless steel in the endoporus of cylinder, is equipped with guiding valve 16 in the endoporus of sleeve, and two O-ring seals 2 14 are provided between person, are leaked to prevent medium.

The top of guiding valve 16 is provided with annular sword side, and the valve port of draining valve is formed with sealing gasket 22, and the Assurance of Size of valve port exists In the case of normal water supply, the ratio pressure of the two is 0.6MPa or so, to ensure the reliability of sealing；Sealing gasket 22 is by screw, pressure Plate 21 is fixed in the groove below 1 time partition wall of valve body；Cylindrical get on the bus in the upper end of guiding valve 16 has screw thread, and is cased with diaphragm 10；Film The inner ring of piece 10 is pressed on by clamp nut 19 and packing ring 20 on the upper surface of 16 outer convex shoulder of guiding valve, in the situation of not water flowing Under, the outward flange of diaphragm 10 and inner ring are located substantially in same level；Piston 17, piston are equipped with the endoporus of guiding valve 16 The 17 upper internal shoulder by guiding valve top positions；Piston 17 is by central shaft, outer piston ring and two straight dowel groups Into there is two mounting hole f between muscle；The lower end of piston 17 is provided with spring 13, and spring force can be by below with the g of osculum two Adjusting bolt Adjusting screw 15 is adjusted；Under spring force, the upper surface of the central shaft of piston 17 lower end with the boss of pressing plate 19 all the time Face contacts, while guiding valve 16 is all the time by 13 1 downward thrusts of spring, therefore in the case of not water flowing, the evagination of guiding valve 16 The lower surface of shoulder is pressed on the upper surface of sleeve 12, and now valve port V is opened completely, and with the aperture of setting；Guiding valve 16 It is drain chamber H4 to pacify spring-loaded space in endoporus.

Operation principle (as shown in Figure 1), it is the location drawing of each parts in the situation lower valve that do not supply water shown in figure, now enters Water Check Valve 3, go out Water Check Valve 4 and close, draining valve 5 is opened, and intermediate cavity H2 passes through several osculums on 1 time quartered of valve body One e communicates with the diaphragm epicoele and drain chamber H4 of draining valve.After water supply, medium initially enters intake antrum H1, and by inclined hole a, The corresponding c of aperture and aperture one, the d of radial direction small through hole one on the b of aperture two, the edge of diaphragm 10 enter the cavity of resorption of draining valve film 10. With the rise of intake antrum H1 hydraulic pressure, when the pressure for acting on the lower section of diaphragm 10 reaches the setting pressure of draining valve spring 13, Band movable pulley 16 is moved upwards, and valve port V is closed, and now intermediate cavity H2 and drain chamber H4 separates.After draining valve is closed, on P1 continues Rise, until Water Check Valve opening will be entered, will then go out Water Check Valve 4 and open, and downstream supply water.

In the case of normal water supply, if intake pressure P1 declines suddenly, during decline, set when (P1-P2) is less than During definite value, draining valve is opened under the promotion of spring 13, the medium in intermediate cavity H2 through the e of osculum one, valve port V, mounting hole f, Drain chamber H4 and the g of osculum two are discharged, and intermediate cavity H2 hydraulic pressure P2 is reduced immediately, when (P1-P2) recovers to setting value, row Water valve is closed again, recovers normal water supply.

When import hydraulic pressure P1 is fallen too low, or be zero, even negative value when, draining valve 5 is opened rapidly, by intermediate cavity H2 Water emptying, while air enters intermediate cavity H2, forms air partition, it is therefore prevented that the generation of siphon refluence, even if now entering Water Check Valve seal failure (such as being blocked by debris) will not also flow backwards.

In the case of normal water supply, if because the reasons such as water hammer cause discharge pressure significantly to raise, now, if water outlet stops Return the good seal of valve 4, then intermediate cavity H2 pressure can raise, if seal failure, intermediate cavity H2 pressure P2 with rise, When (P1-P2) reaches 5 closing presure of draining valve, draining valve 5 is opened, while air enters intermediate cavity H2, forms air partition.

From the above analysis, the present invention is in office why not under sharp operating mode, even if the sealing of two check-valves all destroyeds, all It can effectively prevent from flowing backwards the danger at medium pollution water source.

Water trap function detection device (as shown in Figure 3)：

The present apparatus is arranged on the projection 2 of bottom flange 11 and the lower surface of valve body 1 clamps the position of diaphragm 10, by valve rod 23, O shapes The grade of fastening screw nut 25 part of sealing ring 3 24 and surface knurling forms.The outer peripheral face and the projection two of bottom flange 11 of the lower end of valve body 1 The h of radial direction small through hole two and the j of radial direction small through hole three are drilled with the appropriate location of D2 outer peripheral faces respectively, outer end is stifled with steel ball 9 after brill Extremely, the axis in two holes is on same vertical plane.The L of aperture three is drilled with the lower surface of valve body 1, it is vertical with the h of radial direction small through hole two Intersecting, the L of aperture three end is machined with the conical surface；Hole m is drilled with the D2 of 11 projection of bottom flange two end face, with the j of radial direction small through hole three Intersect vertically, internal thread is machined with the downside of the m of hole, the L of aperture three communicates with hole m, and axis is on the same line.The outward flange of diaphragm 10 Corresponding aperture is provided with, it is concentric with hole m.Valve rod 23 is equipped with the m of hole, valve rod is stairstepping, and epimere is thinner, and top is machined with cone The conical surface of platform, frustum and the L ends of aperture three is close to match somebody with somebody and forms valve port；Stage casing is used as guiding during its up and down motion, O-ring seals 3 24 preventing medium from leaking；Hypomere is machined with external screw thread, is screwed with the internal thread on the downside of the m of hole；Tail end is machined with to turn The square opening of ovable valve stem, fastening screw nut 25 after valve port is shut preventing its loosening.

Under normal circumstances, valve rod 23 is tightened, the frustum of its upper end is in close contact with the taper hole of the L ends of aperture three, valve port Close, now the upper and lower cavity of diaphragm 10 is obstructed.

When checking draining valve function, fastening screw nut 25 is unclamped first, then rotation valve rod 23, open valve port, now The water under high pressure P1 of the cavity of resorption of diaphragm 10 is through aperture j, annular gap i, valve port, the L of aperture three and the epicoele of two h entrance diaphragms of aperture 10, film The hydraulic pressure P2 rises of piece epicoele, when (P1-P2) is less than setting value, draining valve 5 opens draining, tests several times repeatedly, if valve Not draining when bar 23 is tightened, draining during release, then can confirm that draining valve function is normal.Otherwise, draining valve has broken down, should On-call maintenance.Because detection method is convenient, it can at any time detect, can find whether draining valve is faulty, timely processing, prevents early Large amount of sewage flows backwards.

This invention takes the aggregate measures for advantageously reducing flow resistance are as follows：

Permanent magnet and armature are provided with (1) two check-valves, so when valve port is fully open, can be offset nearly The spring pressure of half, is computed, and without magnet and armature, the flow loss of two check-valves is about 0.04MPa, has used about 0.022MPa, reduce 0.018MPa；

(2) on the premise of meeting that entery and delivery port check-valves opens pressure, spring rate is reduced, to reduce valve port whole Spring pressure during opening；

(3) drain valve structure is changed, there is no through upper and lower montant in intermediate cavity；

(4) in order to reduce flow resistance to greatest extent, the present invention particularly payes attention to the design of flow section area and runner, now with DN100 backflow preventer is explained：

A) table 1 is the ratio of main flow section area and nominal dimension area.

Table 1

Note：Each flow section area is not less than the 80% of nominal area in design specification requirement valve

As shown in Table 1, ratio is much larger than 80% requirement, flow section area is big, and flow velocity is with regard to low, and flow resistance and flow velocity Square directly proportional, this is largely effective to reducing flow resistance under high flow velocities.

B) when medium flows in valve pocket, it is all with the contact site of each part or leave position have 30 °~60 ° chamferings or Fillet, to reduce local eddy currents loss.

C) short series length standard is used, to reduce linear loss.

D) valve pocket inwall and each part of intracavitary, all surfaces contacted with flow media are machined, any surface finish Degree is high.

Surveyed through model machine, when velocity of medium is 3m/s, flow resistance loss about 0.32MPa；When flow velocity is 2m/s, flow resistance loss About 0.025MPa, approve for water supply department, available for the relatively low area of pressure of supply water.

Claims (9)

1. a kind of micro- resistance pressure reduction type backflow preventer, has valve body（1）, bonnet,（2）, bottom flange（11）, enter Water Check Valve （3）, go out Water Check Valve（4）And draining valve（5）；

Enter Water Check Valve（3）With go out Water Check Valve（4）It is arranged horizontally in valve body（1）And bonnet,（2）Between intermediate cavity（H2） In, its axis is consistent with valve body intake-outlet axis；

Draining valve（5）It is arranged on valve body lower end face and bottom flange（11）Between, its axis phase vertical with the axis that valve body is imported and exported Hand over, valve body（1）There are some osculums one on lower quartered（e）With drain chamber（H4）Connection；

It is characterized in that：It is described to enter Water Check Valve and to go out Water Check Valve and be each provided with permanent magnet and armature, also use top to have The circlip of opening, to facilitate dismounting to overhaul；

The draining valve is provided with and diaphragm（10）The guiding valve (16) to link into an integrated entity, piston (17) is equipped with the endoporus of guiding valve, The central shaft upper surface of piston is in the presence of spring (13), and the boss lower surface with pressing plate (21) contacts all the time；

Valve body lower end and bottom flange（11）Connecting portion be provided with by intake pressure introduce the through hole of diaphragm cavity of resorption and can make on diaphragm, The water trap function detection device of cavity of resorption connection；

The bottom flange（11）Including the integral lower flange of casting, middle part have sinking cylinder, in position on it is some Projection, the projection include projection one（D1）With projection two（D2）；In bottom flange（11）Cylinder endoporus in close-fitting have sleeve （12）, guiding valve is equipped with the endoporus of sleeve（16）, piston is equipped with the endoporus of guiding valve（17）, piston it is upper by guiding valve The internal shoulder positioning in portion；Bottom flange（11）On be additionally provided with by intake pressure introduce diaphragm cavity of resorption through hole.

2. micro- resistance pressure reduction type backflow preventer according to claim 1, it is characterised in that：The guiding valve（16）Upper end Cylindrical get on the bus has screw thread, diaphragm（10）Inner ring pass through clamp nut（19）And packing ring（20）It is pressed on guiding valve（16）Outer convex shoulder On upper surface, in the case of not water flowing, diaphragm（10）Outward flange and inner ring be located substantially in same level.

3. micro- resistance pressure reduction type backflow preventer according to claim 1 or 2, it is characterised in that：The guiding valve（16）'s Top is provided with annular sword side, with the sealing gasket installed in body base（22）Form the valve port of draining valve, the Assurance of Size of valve port In the case of normal water supply, the MPa of ratio pressure about 0.6 of the two, to ensure the reliability of sealing.

4. micro- resistance pressure reduction type backflow preventer according to claim 1, it is characterised in that：The piston（17）By center Piston ring and two straight dowels outside axle, central shaft form, and have two mounting holes between muscle（f）.

5. micro- resistance pressure reduction type backflow preventer according to claim 1 or 4, it is characterised in that：The piston（17）Under Square spring（13）Lower end be connected to centre and have osculum two（g）Adjusting bolt Adjusting screw（15）On, the Adjusting bolt Adjusting screw（15）Screw togather In the internal thread of guiding valve (16) lower end, to adjust spring force.

6. micro- resistance pressure reduction type backflow preventer according to claim 1 or 2, it is characterised in that：The intake pressure draws Entering the through hole of diaphragm cavity of resorption is：Bottom flange projection one（D1）Outer peripheral face on be drilled with the radial direction small through hole one connected with diaphragm cavity of resorption （d）, steel ball is used after brill（9）Outer end is blocked；Bottom flange bottom surface is drilled with aperture one（c）, with radial direction small through hole one（d）Vertical phase Hand over, and with positioned at valve body（1）The upper aperture two connected with intake antrum（b）On same center line；Pass through valve body（1）Upper and import The inclined hole of chamber connection（a）, aperture two（b）, diaphragm（10）On corresponding through hole and aperture one（c）, radial direction small through hole one（d）, By intake pressure（P1）It is incorporated into diaphragm（10）Cavity of resorption.

7. micro- resistance pressure reduction type backflow preventer according to claim 2, it is characterised in that：Bottom flange（11）Lower flange There is boss upper surface, and boss is provided with and can easily exclude to accumulate in the blowdown bolt of dirt in diaphragm cavity of resorption（18）.

8. micro- resistance pressure reduction type backflow preventer according to claim 1 or 2, it is characterised in that：Water trap Function detection Device is arranged on the projection two of bottom flange（D2）And valve body（1）Lower surface clamps diaphragm（10）In the intercommunicating pore at position, including valve Bar（23）, O-ring seals three（24）And fastening screw nut（25）；The valve rod（23）For stairstepping, epimere is thinner, and top is machined with Frustum, stage casing are used as guiding during its up and down motion, and with O-ring seals three（24）Prevent medium from leaking, hypomere is machined with outer There is fastening screw nut screw thread, end（25）To prevent valve rod from loosening after valve port is shut.

9. micro- resistance pressure reduction type backflow preventer according to claim 8, it is characterised in that：Described intercommunicating pore includes valve Body（1）Lower end periphery face and bottom flange projection two（D2）Radial direction small through hole two is drilled with the appropriate location of outer peripheral face respectively（h）With Radial direction small through hole three（j）, steel ball is used in outer end after brill（9）Block, the axis of holes is on same vertical plane；Valve body（1）'s Aperture three is drilled with lower surface（L）, with radial direction small through hole two（h）Intersect vertically, aperture three（L）End be machined with and valve rod （23）The conical surface that end frustum coordinates, so as to form valve port；Bottom flange projection two（D2）End face on be drilled with and valve rod coordinate Hole（m）, the hole（m）With radial direction small through hole three（j）Intersect vertically, with aperture three（L）Communicate and concentric, diaphragm（10）Outward flange Corresponding aperture is provided with, with hole（m）With one heart, hole（m）Downside be machined with and valve rod（23）The internal thread that external screw thread coordinates.