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How to Find Gear Modification Coefficient

How to calculate gear modification coefficient:
1. Total displacement coefficient:

Total displacement coefficient

Total displacement coefficient

2. Coefficient of variation of center distance:

Coefficient of variation of center distance

Coefficient of variation of center distance

3. Coefficient of change of addendum height:

Coefficient of change of addendum height

Coefficient of change of addendum height

4. The modification coefficient table of the number of teeth z=8~20 cylindrical gear:

The modification coefficient table of the number of teeth z=8~20 cylindrical gear

The modification coefficient table of the number of teeth z=8~20 cylindrical gear

Gear Modification Coefficient

Gear Modification Coefficient

What is the gear modification coefficient

The standard gear transmission has some limitations:
(1) Limited by undercutting, the number of teeth should not be less than Zmin, making the transmission structure not compact enough;
(2) Not suitable for occasions where the installation center distance a’is not equal to the standard center distance a. When a'<a, it cannot be installed, when a’>a, although it can be installed, it will produce excessive backlash and cause shock and vibration, which will affect the stability of the transmission;
(3) When a pair of standard gears are driven, the pinion has a small tooth root thickness and more meshing times, so the strength of the pinion is low, and the wear of the tooth root is also serious. Therefore, the pinion is easy to be damaged, and it also limits The carrying capacity of the big gear.
In order to improve the performance of gear transmission, a shifted gear appeared. As shown in the figure, when the tooth top line of the rack slotting tool exceeds the limit meshing point N1, the cut gear will undercut. If the rack is inserted away from the wheel center O1 for a certain distance (xm) and the tooth top line no longer exceeds the limit point N1, the cut gear will not undergo undercutting, but at this time the index line of the rack and the division of the gear The degree circle is no longer tangent. The gear cut after changing the relative position of the tool and the tooth blank is called the displacement gear, the distance xm the tool moves is called the displacement, and x is the displacement coefficient. The displacement of the tool away from the wheel center is called positive displacement, at this time x>0; the displacement of the tool moving closer to the wheel center is called negative displacement, at this time x<0. The standard gear is the gear with the modification coefficient x=0.

what is bevel gear?

The bevel gear is used to transmit the movement and power between the two intersecting shafts. In general

bevel gear

bevel gear

machinery, the angle of intersection between the two shafts of the bevel gear is equal to 90° (but it may not be equal to 90°). Similar to cylindrical gears, bevel gears have indexing cones, addendum cones, tooth root cones and base cones. The cone has a big end and a small end, and the circle corresponding to the big end is called the index circle (its radius is r), the addendum circle, the root circle and the base circle. The movement of a pair of bevel gears is equivalent to a pair of pitch cones for pure rolling.
Application field
Industrial transmission equipment, vehicle differential
Classification
Straight tooth, helical tooth, curved tooth
Features
Noise reduction, shock absorption, light weight, low cost, etc.

Bevel gear actuator is coded 5 in the valve naming system in China, see link: https://www.tanghaivalve.com/valve-model-establishment-and-meaning/

Unit One , valve type (code name):

butterfly valve safety valve Diaph-ragm valve ball valve gate valve check valve plug valve Pressure reducing valve globe valve filter Disch-arge valve
D A G Q Z H X Y J GL FL

Unit two, valve drive mode (code name):

drive mode Electro-magne-tism Electro-magnetic hydraulic Electro-hydraulic tur-bine Spur gear Bevel gear pneu-matic Hydr-aulic Gas-hydr-aulic elec-tric han-dle Hand-wheel
code 0 1 2 3 4 5 6 7 8 9

Unit three, valve connection method (code name):

connection internal thread external thread two different connections flange welding wafer clamp ferrule
code 1 2 3 4 6 7 8 9

1. Formation of tooth profile
The formation of the tooth profile of bevel gears is similar to that of cylindrical gears, except that the base cone is

The formation of spherical involute

The formation of spherical involute

used instead of the base cylinder. As shown on the right, the generating surface S is tangent to the generatrix of the base cone. When the generating surface S is purely rolling along the base cone, any straight line OK on the

generating surface contacting the generatrix ON of the base cone will form an involute curved surface in space. This curved surface is the tooth profile curved surface of the straight bevel gear. The trajectory of each point on the line OK is an involute (the involute at the vertex O is a point). Each point on the involute NK is equidistant from the cone O, so the involute must be on a spherical surface centered on the cone O and the radius is OK, that is, NK is a spherical involute.
2. Back cone and equivalent gear
The following figure shows a pair of special bevel gear drives. Among them, the number of teeth of wheel 1 is, the indexing circle radius is, and the reference cone angle is; the number of teeth of wheel 2 is, the indexing circle radius is, the indexing cone angle=90°, and the indexing cone surface is A plane, this kind of gear is called a crown gear.

Equivalent gear of bevel gear

Equivalent gear of bevel gear

The large end node P of the wheel 1 is used as the vertical line of the indexing cone generatrix OP, crossing its axis and point O1, and then taking O1 point as the cone tip and O1P as the generatrix, making a cone tangent to the large end of wheel 1 , Call this cone the back cone of wheel 1. In the same way, the back cone of wheel 2 can be made. Since wheel 2 is a crown wheel, its back cone becomes a cylindrical surface. If the back cones of the two wheels are expanded, the back cone of wheel 1 will be expanded into a sector gear, and the back cone of wheel 2 will be expanded into a rack, that is, after the back cone is expanded, the two are equivalent to gears and teeth. Strip meshing transmission. According to the Fan Cheng principle, when the tooth profile of the rack (that is, the back cone of the crown wheel) is a straight line, the tooth profile of the wheel 2 on the back cone is an involute.

Imagine filling up the gap of the unfolded sector gear, and you will get a cylindrical gear. This imaginary cylindrical gear is called the equivalent gear of the bevel gear, and the number of teeth Zv is called the equivalent number of teeth of the bevel gear. The tooth profile of the equivalent gear and the tooth profile of the bevel gear on the back cone (that is, the big end tooth profile) are consistent, so the modulus and pressure angle of the equivalent gear are consistent with the modulus and pressure angle of the large end of the bevel gear. As for the equivalent number of teeth, it can be obtained as follows:

As can be seen from the figure above, the index circle radius of the equivalent gear of wheel 1 is
γv1=γ1/cosδ1=z1m(2cosδ1)

So
zv1=z1/cosδ1

For any bevel gear there is
zv=z/cosδ

With the help of the concept of bevel gear equivalent gear, the correct meshing condition of a pair of bevel gears should be that the modulus and pressure angle of the large ends of the two wheels are equal respectively; the coincidence degree of a pair of bevel gear transmission can be calculated approximately according to the coincidence degree of the equivalent gear transmission ; In order to avoid undercutting of gear teeth, the minimum number of teeth for bevel gears without undercutting zmin=zvmincosδ
3. Analysis of gear tooth force
Similar to the cylindrical gear, the nominal normal load Fn is decomposed into the circumferential force Ft1, the radial force Fr1 and the axial force Fa1 at the average index circle of the pinion gear. The direction of each force is shown in the figure on the right, and then according to the force balance The geometric relationship between the conditions and the forces is calculated, namely

bevel gear force analysis

bevel gear force analysis

Force Analysis of Straight Bevel Gear

Force Analysis of Straight Bevel Gear

 

The force analysis on the big gear is similar to that on the small gear.
4. Geometric parameters and calculations
Bevel gears use the big end parameter as the standard value, so when calculating their geometric dimensions, the big end should also prevail. As shown in the figure below, the index circle diameters of the two bevel gears are respectively
d1=2Rsinδ1, d2=2Rsinδ2

In the formula, R is the distance from the tip of the indexing cone to the large end, which becomes the cone distance; δ1 and δ2 are the indexing cone angles of the two bevel gears (referred to as the cone angle for short).
The transmission ratio of the two wheels is

i12=w1/w2=z2/z1=d2/d1=sinδ2/sinδ1

When the shaft angle Σ=90° between the two bevel gears, the above formula becomes due to δ1+δ2=90°

i12=w1/w2=z2/z1=d2/d1=cotδ1=tanδ2

Geometry of bevel gear transmission

Geometry of bevel gear transmission

When designing bevel gear transmission, the value of the cone angle of the two wheels can be determined according to the above formula according to the given transmission ratio.

As for the size of the bevel gear tip cone angle and the tooth root cone angle, they are related to the head clearance requirements of the two bevel gears when they are meshed and driven. According to national standards (GB/T 12369-1990, GB/T12370-1990), equal head-clearance bevel gears are now used for transmission. The head clearance of the two wheels is equal from the big end to the small end of the gear. The cones of the degree cone and the root cone coincide at one point. However, because the generatrix of the tooth tip cone of the two wheels is parallel to the generatrix of the tooth root cone of the other bevel gear meshing with it, the cone tip no longer coincides with the indexing cone cone tip. This kind of bevel gear is equivalent to reducing the tooth tip height of the small end of the tooth, thereby reducing the possibility of the tooth tip being too sharp; and the tooth root fillet radius is larger, which is beneficial to improve the load capacity of the tooth, tool life and storage Oil lubrication.

TH Valve is a professional manufacturer of butterfly valvegate valvecheck valveglobe valveknife gate valve, ball valve with API, JIS, DIN standard, used in Oil, Gas, Marine industry, Water supply and drainage, fire fighting, shipbuilding, water treatment and other systems, with Nominal Diameter of DN50 to DN1200, NBR/EPDM/VITON, Certificates & Approvals: DNV-GL, Lloyds, DNV, BV, API, ABS, CCS. Standards: EN 593, API609, API6D

Related news/knowledge:
Form and types of Gear transmission
What is the positive transmission of gears
what is Spur gear?
What is the gear modification coefficient

what is Spur gear?

Spur gear is a classification of gears. According to the relative position and tooth direction of a pair of gear axes (whether the two circles are parallel), it can be divided into plane gear rotation and space gear rotation; according to

Spur gear

Spur gear

the working conditions of the gears, it can be divided into open transmission and closed transmission; according to gear teeth or tooth profile. The gear is divided into straight teeth, helical teeth, herringbone teeth, or straight teeth, curved teeth, as per the shapes.

The code name is 4 for valve drive mode. see details at: https://www.tanghaivalve.com/valve-model-establishment-and-meaning/

Unit One , valve type (code name):

butterfly valve safety valve Diaph-ragm valve ball valve gate valve check valve plug valve Pressure reducing valve globe valve filter Disch-arge valve
D A G Q Z H X Y J GL FL

Unit two, valve drive mode (code name):

drive mode Electro-magne-tism Electro-magnetic hydraulic Electro-hydraulic tur-bine Spur gear Bevel gear pneu-matic Hydr-aulic Gas-hydr-aulic elec-tric han-dle Hand-wheel
code 0 1 2 3 4 5 6 7 8 9

Unit three, valve connection method (code name):

connection internal thread external thread two different connections flange welding wafer clamp ferrule
code 1 2 3 4 6 7 8 9

Classification
Straight cylinder/spur gear
Meshing mode: external meshing, internal meshing, gear and rack
Basic characteristics: The tooth profile contact line is a straight line parallel to the axis. A pair of tooth profiles enter or exit the mesh at the same time along the tooth width, which is likely to cause shock and noise, and the transmission stability is poor.

Straight bevel gear:
Pitch cone, index cone, tooth tip cone, tooth root cone, base cone; used for transmission between intersecting two shafts, the gear teeth are distributed along the cone surface, and the size of the starting gear teeth gradually decreases toward the cone tip.
In order to enable the gear to rotate in both directions, the tooth profile on both sides of the gear tooth is composed of involute surfaces with the same shape and opposite directions. The names and symbols of each part are: addendum circle, tooth root circle, tooth Slot, tooth thickness, tooth pitch, modulus m, index circle d, tooth top and tooth root, top clearance

Gears are divided into spur gears, helical gears, herringbone gears, and curved gears according to the shape of the tooth line. The spur gears are gears whose teeth are parallel to the axis.

Surveying method:
The spur gear is one of the most common gears in actual production and use. Damage is inevitable during use. Therefore, it is necessary to make a new gear that is the same as the original one. For various reasons, the customer cannot provide the required spur gear. In order to ensure the normal use of the processed products, the gear drawings need to be accurately surveyed and mapped. The surveying and mapping work is a complicated task. Since there are few data on the surveying and mapping of spur gears, it is naturally inconvenient to consult. The work experience and methods of surveying and mapping spur gears in several actual production are summarized by the operation. The introduction is as follows:

First of all, although there are many parameters and dimensions of spur gears, the standard system of various gears stipulates the modulus or diameter pitch as the calculation basis for other parameters and the dimensions of each part. Therefore, the surveying and mapping work should make every effort to accurately determine the size of the modulus or the diametral pitch. At the same time, the pressure angle is the basic parameter to determine the tooth profile, and accurate determination is equally important.

Secondly, we need to understand the usage and production country of the gear being surveyed, so that we can estimate the standard system adopted by this gear. Generally speaking, China, Japan, Germany, France, Czech Republic, and the former Soviet Union all adopt the modular system. You can also observe the tooth profile of the gear. If the tooth profile is curved and the bottom of the tooth groove is narrow and arc-shaped, it can be preliminarily judged as a modular system. The standard pressure angle is mostly 20 degrees; the United States and the United Kingdom adopt diameter control, and the standard pressure angles are 14.5 degrees and 20 degrees. Observing that the tooth profile is relatively straight and the bottom of the tooth groove is wider and the arc is small, it can be preliminarily judged as the diameter control. The pressure angle is 14.5 degrees. You can also use gear hobs or standard rack samples to determine which pressure angle is. If you know the above conditions, you can actually survey and map:

(1) Method of measuring the diameter of the addendum circle Dm

First count the number of teeth Z of the gear, and then use a vernier caliper to measure the diameter Dm of the addendum circle. If it is determined that the gear is a modular standard tooth profile, its modulus:

m = Dm/Z+2

If it is determined that the gear is a standard tooth profile with diameter control, its diameter pitch is

Dp=25.4*(Z+2)/ Dm

However, it should be noted that if the number of teeth of the gear is even, it can be directly measured; if the number of teeth is odd, the measured size is not the addendum diameter Dm, but two teeth from the tip of a tooth to the opposite tooth space. The distance D between the intersection of the face and the addendum circle is smaller than the diameter of the addendum circle. Usually, Dm is multiplied by the correction coefficient k to get the addendum circle diameter D, namely:

Dm=k*D

In practice, the diameter of the addendum circle calculated by the odd-numbered gear addendum circle diameter correction coefficient k (Table 1) is generally small. The diameter of the addendum circle calculated using the corrected correction coefficient k (Table 2) according to the above formula is more Close to the real value, Table 2 is more accurate than Table 1, and the number of teeth is finer, for reference.

fig.1-Odd tooth gear Addendum circle diameter Correction coefficient K

fig.1-Odd tooth gear Addendum circle diameter Correction coefficient K

fig.2-Correction coefficient after correction k

fig.2-Correction coefficient after correction k

If the odd-numbered gear is not a gear shaft but has a hole, you can also measure the inner hole diameter d and the distance H from the hole wall to the tooth tip, and get the tooth tip circle diameter by the following formula:

Dm=2*H+d

(2) Method of measuring the height of the tooth

When the gear is inconvenient to measure the diameter of the addendum circle due to large modulus, tooth punching, etc., the full height h of the tooth can be measured to determine the modulus or diametral pitch. The total tooth height h can be measured with the depth tail needle of a vernier caliper, and other depth measuring tools are also available, depending on the site conditions; if the gear has a hole, the tooth total height h can be obtained indirectly by measuring the inner hole wall to the tooth tip and tooth root The subtraction of the distance is the total tooth height h, and the modulus or diametral pitch is calculated as follows:

m=h/2f+c Dp=25.4*(2f+c)/h

f:: Addendum height coefficient c: Radial clearance coefficient

f, c can be found by checking the gear standard system parameter table[3]

(3) Method of measuring center distance A

When the gear teeth are sharp, worn, or rolled, the above two methods cannot be measured. At this time, we can ask the customer to provide the center distance A of the two paired gears and the number of teeth of the two gears. These are easy to do. Calculate the modulus or diametral pitch as follows:

m=2*A/Z1+Z2 Dp=25.4*(Z1+Z2)/2*A

Z1, Z2: Number of teeth of matched gear

The modulus or diametral pitch calculated by any one of the three methods is compared with the standard modulus or diametral pitch series, and the closest one is fine.

The above are the commonly used methods for surveying and mapping spur gears in actual work. It is best to use two methods to check each other, so that the determined modulus or diameter section is more accurate, and the surveying and mapping work is basically completed. Special attention: The above surveying and mapping methods are carried out under the condition that we can pre-determine or investigate the standard system adopted by the gear. If the gear’s “all conditions are unknown”, the above methods can only be referred to, and then comprehensively judged by other means. It is believed that the above several surveying methods will be helpful to colleagues who have just joined the work soon or for the first time to survey and map spur gears. It is worth referring to.

TH Valve is a professional manufacturer of butterfly valvegate valvecheck valveglobe valveknife gate valve, ball valve with API, JIS, DIN standard, used in Oil, Gas, Marine industry, Water supply and drainage, fire fighting, shipbuilding, water treatment and other systems, with Nominal Diameter of DN50 to DN1200, NBR/EPDM/VITON, Certificates & Approvals: DNV-GL, Lloyds, DNV, BV, API, ABS, CCS. Standards: EN 593, API609, API6D

Related news/knowledge:
what is bevel gear?
What is the positive transmission of gears
Form and types of Gear transmission
What is the gear modification coefficient

Description of lining material for rubber lining valve

Overview of rubber-lined valves:
Rubber-lined valve (lined valve) is a valve suitable for pipelines containing corrosive media and high sealing requirements. Generally, the applicable temperature should not be too high, and it is not suitable for use in media

double-wing-check-valve-3

double-wing-check-valve-3

containing particles to avoid scratches. Scratches or scratches the sealing surface, causing the valve to leak. Rubber-lined valve is a kind of plastic product produced by the chemical reaction of many chemical substances. The main materials are: soft rubber, hard rubber, butyl rubber, natural rubber, EPDM rubber, fluorine rubber, Lining silicone rubber, etc., its main working purposes are: diversion, adjustment, throttling, cut-off, check, diversion, overflow, etc., which means that as long as it is a general fluid valve, it can be controlled.

The main lining materials of rubber-lined valves:
【Neoprene, Code CR】
Applicable temperature: -10℃~105℃ Animal oil, vegetable oil, inorganic lubricating oil and corrosive slurries with a wide range of pH value, good wear resistance.
【Soft Rubber Code BR】
Applicable temperature: -10℃~85℃
Applicable medium: good wear resistance. Mainly used for sulfuric acid below 50%, sodium hydroxide, potassium hydroxide, neutral salt bath solution and ammonia solution, cement, clay, cinder ash, granular fertilizer and solid fluids with strong abrasiveness, and thick viscous liquids of various concentrations Wait. _
【Butyl Rubber Code IIR】 Applicable temperature: -10℃~120℃
Applicable medium: corrosion resistance and wear resistance. Can withstand most organic acids, alkalis and hydroxide compounds, inorganic salts and inorganic acid element gases, alcohols, aldehydes, ethers, ketones, esters, etc., ≤30% sulfuric acid, phosphoric acid, hydrofluoric acid, animal oil , Vegetable oil, caustic alkali and a variety of lipids. _
【Hard Rubber Code NR】 Applicable temperature: -10℃~85℃
Applicable medium: hydrochloric acid, fluorosilicic acid, formic acid and phenolic acid, hydrochloric acid, 30% sulfuric acid, 50% hydrofluoric acid, except strong oxidants (such as organic solvents such as acid, chromic acid, concentrated sulfuric acid and hydrogen peroxide) Acid, 80% phosphoric acid, alkali, salt, metal plating solution, sodium hydroxide, potassium hydroxide, neutral salt solution, 10% sodium hypochlorite, wet chlorine, ammonia, most alcohols, organic acids and aldehydes, etc.

Conversion of valve nominal diameter and inch | comparison table

Valve nominal diameter|valve nominal diameter
Definition of valve nominal diameter:

ductile iron, DI, butterfly valve, manufacturer, center line, TH valve

ductile iron, DI, butterfly valve, manufacturer, center line, TH valve

Nominal diameter (or nominal diameter), also known as average outer diameter, refers to the size of all piping accessories in the piping system. The nominal diameter is a convenient round integer for reference. The nominal diameter of the valve is marked with a number followed by the letter DN. DN represents the internal diameter of the pipe in millimeters. For example, DN50 is 50 millimeters. The American standard valve is usually expressed in inches (“), and the fractional valve is to express the internal diameter of the pipe in inches. The conversion formula is 1”=25.4mm, such as 8” is equivalent to the domestic DN200mm.

Valve nominal diameter comparison table:
The nominal diameter of the valve (NPS-NOMINAL PIPE SIZE) is not necessarily the same as the diameter of the flow channel. For the selection of its size, the required Cv value is calculated from the conditions of the conveying fluid, and then the Cv value (refer to the manufacturer’s catalog) is used to select a suitable valve The nominal diameter (NPS) is the nominal inner diameter that characterizes the valve diameter. The national standard is expressed by DN and the unit is mm. The American standard is expressed in inches. The conversion relationship between inch NPS and metric DN is as follows:

No. inch DN/mm No. inch DN/mm No. inch DN/mm
1 1/8 4 17 10 250 33 42 1050
2 1/4 8 18 12 300 34 48 1200
3 3/8 10 19 14 350 35 54 1350
4 1/2 15 20 16 400 36 60 1500
5 3/4 20 21 18 450 37 64 1600
6 1 25 22 20 500 38 72 1800
7 11/4 32 23 22 550 39 80 2000
8 11/2 40 24 24 600 40 84 2100
9 2 50 25 26 650 41 88 2200
10 21/2 65 26 28 700 42 96 2400
11 3 80 27 30 750
12 31/2 90 28 32 800
13 4 100 29 34 850
14 5 125 30 36 900
15 6 150 31 38 950
16 8 200 32 40 1000

TH Valve is a professional manufacturer of butterfly valvegate valvecheck valveglobe valveknife gate valve, ball valve with API, JIS, DIN standard, used in Oil, Gas, Marine industry, Water supply and drainage, fire fighting, shipbuilding, water treatment and other systems, with Nominal Diameter of DN50 to DN1200, NBR/EPDM/VITON, Certificates & Approvals: DNV-GL, Lloyds, DNV, BV, API, ABS, CCS. Standards: EN 593, API609, API6D

Related news /knowledge:
Comparison table of valve diameter (DN) and pipe diameter;
Classification and introduction of pipe thread-(3);
Classification and introduction of pipe thread-(1);
Classification and introduction of pipe thread-(2)

Comparison table of valve diameter (DN) and pipe diameter

The size of the valve caliber has an inevitable relationship with the size of the pipeline. It is usually said that the pipe diameter (outer diameter) is matched with the valve. The valve diameter needs to be calculated according to the actual parameters. Generally speaking, the pipeline will be larger, and the valve actually needs to be smaller. It mainly depends on the flow rate to be controlled by the valve position, and the pipeline size only needs the flow capacity.
(1) Comparison table of pipe fitting size and valve diameter and inches:

Diameter/inch DN (Norminal diameter) mm pipe OD (mm)
1/4 8 13.7
3/8" 10 17.14
1/2" 15 21.3
3/4" 20 26.7
1" 25 33.4
1.2" 32 42.2
1.5" 40 48.3
2" 50 60.3
2.5" 65 73
3" 80 88.9
4" 100 114.3
5" 125 141.3
6" 150 168.3
8" 200 219.1
10" 250 273
12" 300 323.8
14" 350 355.6
16" 400 406.4

(2) Valve diameter DN (nominal diameter) corresponds to the outer diameter of the pipe Ф (mm):

Norminal diameter/DN pipe OD small pipe OD big Norminal diameter/DN pipe OD small pipe OD big
15 18 22 350 360 377
20 25 27 400 406 426
25 32 34 450 457 480
32 38 42 500 508 530
40 45 48 600 610 630
50 57 60 700 720
65 73 76 800 820
80 89 89 900 920
100 108 114 1000 1020
125 133 140 1200 1220
150 159 168 1400 1420
200 219 219 1600 1620
250 273 273 1800 1820
300 324 325 2000 2020

TH Valve is a professional manufacturer of butterfly valvegate valvecheck valveglobe valveknife gate valve, ball valve with API, JIS, DIN standard, used in Oil, Gas, Marine industry, Water supply and drainage, fire fighting, shipbuilding, water treatment and other systems, with Nominal Diameter of DN50 to DN1200, NBR/EPDM/VITON, Certificates & Approvals: DNV-GL, Lloyds, DNV, BV, API, ABS, CCS. Standards: EN 593, API609, API6D

Related news/knowledge:
Conversion of valve nominal diameter and inch | comparison table;
Classification and introduction of pipe thread-(2);
Electric flange ball valve installation instructions;
What is a Single-disc swing check valve

Working principle diagram of swing check valve

Working principle diagram of swing check valve
Swing check valve, also known as check (flow) valve, is an automatic valve used on one-way flow pipelines to prevent the medium from flowing back. It depends on the pressure of the pipeline medium to open or close the valve. It can be divided into single valve type , Double valve type and multi valve type, are one of the more commonly used valves. Swing check valves are generally suitable for pipelines with relatively clean fluid media. They are not suitable for

swing-check-valve-working-principle-diagram

swing-check-valve-working-principle-diagram

working conditions with high viscosity or solid particles. Otherwise, the check valve will be insensitive to opening and cannot achieve a complete seal. The answer is not reliable enough. The swing check valve only allows the medium to flow in one direction, which can effectively prevent the medium from flowing back to prevent accidents.

The working principle of the swing check valve:
The disc of the swing check valve and the rocker are connected together, and can rotate a certain angle around the pin shaft. When the pipeline fluid flows in the specified direction (from left to right), the inlet pressure of the disc is higher than the outlet pressure. At this time, the disc is pushed away from the valve seat and rotates around the pin to a certain position, and the valve is in the open state. When the pressure difference between the two sides of the valve flap decreases to a certain level, the valve flap falls and returns to the closed state. When the fluid flows from right to left, that is, reverse flow, the pressure on the right side of the valve disc is higher than the pressure on the left side, and the force generated by the pressure difference on both sides presses the valve disc on the valve seat, and the fluid cannot pass through, the medium Can not flow back; and the greater the fluid pressure, the tighter the sealing surface is, and the better the sealing effect. To

The installation position of the swing check valve is not restricted. It can be installed horizontally in the pipeline, or on a vertical or inclined pipeline, but if it is installed on a vertical pipeline, the flow direction of the medium should be from bottom to top.

TH Valve is a professional manufacturer of butterfly valvegate valvecheck valveglobe valveknife gate valve, ball valve with API, JIS, DIN standard, used in Oil, Gas, Marine industry, Water supply and drainage, fire fighting, shipbuilding, water treatment and other systems, with Nominal Diameter of DN50 to DN1200, NBR/EPDM/VITON, Certificates & Approvals: DNV-GL, Lloyds, DNV, BV, API, ABS, CCS. Standards: EN 593, API609, API6D

Related news/knowledge:
Basic knowledge of valve;
What is double plate swing check valve;
Butterfly valve use principle and installation instructions;
Wafer type double disc swing check valve introduction

Working principle diagram of lift check valve

Lifting check valve structure:

Lifting check valve is a kind of valve that prevents pipeline media from flowing back, mainly composed of valve body, valve seat, valve flap, valve cover and other related parts. The lift check valve is equipped with a spring to ensure that the disc is always in a dynamic equilibrium state under the action of the spring. Regardless of the medium pressure at the inlet of the valve, the valve can maintain a balanced operation.

lift check valve Working principle diagram

lift check valve Working principle diagram

The working principle of the lift check valve:

The lift check valve has a guide rod on the disc, which can move up and down freely in the guide hole of the valve cover. When the pipeline medium flows in in the specified direction (from left to right), and the pressure below the valve flap exceeds the pressure above it, push the valve flap to rise along the center line of the guide hole of the valve cover, and the valve will automatically open to allow the medium to flow; if the fluid flows from the right to the right Left flow, that is, when it flows backward, the pressure above the valve flap is greater than the pressure below it. The pressure difference between the upper and lower pressures and the weight of the valve flap press the valve flap on the valve seat, so that the medium cannot pass through, that is, the fluid cannot flow back; and pipeline fluid The greater the pressure, the tighter the sealing surface is, and the better the sealing effect.

The seat sealing surface of the lift check valve can be welded, or it can be made into a seat sealing ring and then expanded or threaded on the valve body; when the valve body is made of stainless steel, the sealing surface can also be on the valve body It is directly processed from above. The sealing surface of the disc can be directly processed on the disc, or can be processed after surfacing or welded on the disc with the inner and outer periphery of the sealing ring. The straight-through lift check valve can only be installed on the pipeline in a balanced way, and the center line of the valve flap is vertical to the horizontal plane, while the vertical lift check valve is not subject to this restriction.

What is butt welding? (9)- New technology of flash butt welding

New technology of flash butt welding
1) Program-controlled reduced-voltage flash butt welding is characterized by the use of higher secondary no-load voltage at the beginning of the flash to facilitate the initiation of the flash. When the end surface temperature rises, the low-voltage flash is used and maintained The flash speed remains unchanged to improve thermal efficiency.

flash butt welding-schematic diagram

flash butt welding-schematic diagram

When approaching the upsetting, increase the secondary voltage to make the flash stronger to increase the self-protection effect.
Program-controlled reduced-voltage flash butt welding is compared with preheated flash butt welding. It has the advantages of short welding time, low power required, and uniform heating.

2) Pulse flash butt welding. The characteristic of this welding method is that in the stroke of the moving clamp, a reciprocating vibration stroke is superimposed through the hydraulic vibration device, the amplitude is 0.25-1.2mm, and the frequency is 3-35Hz. Tune. Due to the vibration, the end face of the weldment is alternately short-circuited and pulled apart, resulting in a pulse flash.

Compared with ordinary flash butt welding, pulse flash butt welding has no spontaneous blasting of the lintel, the splashed particles are small and the flame is shallow, so the thermal efficiency can be more than doubled, and the upsetting allowance can be reduced to 2/3-1/ 2.

The above two methods are mainly to meet the needs of flash butt welding of large section workpieces.

3) Rectangular wave flash butt welding Compared with power frequency AC sine wave flash butt welding, this welding method can significantly improve the stability of the flash. Because the sine wave power supply will instantly interrupt the flash when the voltage is close to zero, and the rectangular wave can evenly produce the flash in the full cycle. It has nothing to do with the voltage phase.

The number of flashes per unit time of the rectangular wave power supply is 30% higher than that of power frequency AC, the sprayed metal particles are fine, the flame is shallow and the thermal efficiency is high. The rectangular wave frequency can be adjusted within the range of 30-180Hz. This method is mostly used for continuous flash butt welding of thin plates and aluminum alloy wheels.

TH Valve is a professional manufacturer of butterfly valvegate valvecheck valveglobe valveknife gate valve, ball valve with API, JIS, DIN standard, used in Oil, Gas, Marine industry, Water supply and drainage, fire fighting, shipbuilding, water treatment and other systems, with Nominal Diameter of DN50 to DN1200, NBR/EPDM/VITON, Certificates & Approvals: DNV-GL, Lloyds, DNV, BV, API, ABS, CCS. Standards: EN 593, API609, API6D

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