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Breather valves

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Description

Breather valves are an integral equipment of vertical tanks, which ensures explosionproof operation. In storage process of petroleum products or loading-unloading operations evaporation and vapor formation in the gas space occur. The pressure can also change within 24 hours due to enviromental temperature shift. Some operating processes are accompanied by air ingress from the outside. All these processes ("breathing") lead to pressure boost in the gas space, which can destroy the shell, force out the roof or lead to an explosion. To avoid this, breathing and safety valves are installed.

The purpose of breathing valves

In accordance with GOST 31385-2016 "Vertical cylindrical steel tanks for oil and petroleum products. General technical specifications" and STO-SA-03-002-2009 "Rules for design, manufacture and erection of vertical cylindrical steel tanks for oil and petroleum products" each tank must be equipped with a breathing valve.

Their main function is the regulation of pressure in the gas space or vacuum in vertical tanks.

In addition, they perform the following functions:

  • maintaining of structural integrity
  • reduction of atmospheric evaporation loss
  • fire and explosion protection
  • reduction in environmental pollution
  • intrusion of dust, sand and other particles prevention
  • prevention of upper and saturated lower layers mixing

Regulatory requirements for breather valves

  • fixed operating value shall not exceed 20% of the tank pressure
  • the throughput capacity should not be less than the capacity during loading-unloading operations with account of vapor formation during the oil migration, enviromental and gas space temperature shift

Types of breathing valves

Breathing valves are of two types:

  • with mechanical shutter
  • with hydraulic gate, which are used as safety valves

Design and function of breathing valves with mechanical shutter

Breathing valves with mechanical shutter are represented by several types:

  • the breathing combination valve (KDS) with disk-reflector
  • the combined mechanical breather valve SMDK
  • the breathing enclosed valve KDZT
  • the mechanical breathing valve KDM with internal flame arrestor
  • the impermeable breathing mechanical valve NDKM

Mechanical breather valves differ in throughout capacity, set pressure and seating. Thus, SMDK can be installed on horizontal tanks, KDZT are used in vapor recovery systems of vertical tanks for flammable oil products, KDS and KDM are used with mainly with light oil products.

The principle of action is vapor surplus release or air supply from the atmosphere. Each valve has a normally closed shutter. At breathing (when evaporating) or filling loss the shutter plate is raised from the seat. The limit operating value is set at overpressure of the gas-air mixture or exceeding the vacuum.

Several requirements are applied to the breathing valves:

  • the contact surfaces of the shutters, plates, fastening elements, seats must be impermeable, which is achieved due to their manufacture of materials that have low adhesive properties
  • to avoid inner condensate storing the valve should have a minimum number of horizontal surfaces
  • anticorrosive surface treatment is necessary, as the mass of plates may be reduced resulting from the corrosion

Technical description of the breathing combination valve (KDS)

The KDS valves are installed on vertical tanks to regulate pressure during loading-unloading operations and operating temperature changes. For more reliable operation, a disc-reflector and a fire safety device are provided.

The principle of operation is to open the shutter if the designed operating values are achieved and closing it when reduced. If necessary, it is possible to adjust it to the operating mode of the safety valve.

The specified service life of the KDS is 15 years, after which it is recommended to replace it with the possible changes in the volume of loading-unloading operations. They are manufactured in climatic categories N and NF, placement category 1. When operating in a cold climate, it is possible to install the automatic heating system, which provides the operating temperature of the fire safety device.

KDS-1500 drawing Criteria KDS-1500/150 KDS-1500/200 KDS-1500/250 KDS-1500/350 KDS-1500/500
Breathing combination valve drawing Diameter Nominal DN 150 200 250 350 500
Pressure, Pa (mm w.g.) 2000(200)
Vacuum, Pa (mm w.g.) 250 (25)
Actuation pressure, Pa (mm w.g.) 1500-1600 (150-160)
Actuation vacuum, Pa (mm w.g.) 100-150 (10-15)
Throughput capacity, m3/h 450 750 1000 1300 1500
Area of seat passage, sm2 940
Area of vacuum seat passage, sm2 4 × 475 = 1900
Overall dimensions, mm, max:  
-length 900
-width B 900
-height H 800 900 900 900 800
Connection sizes, mm D 260 315 370 485 640
D1 225 280 335 445 600
d 18 18 18 22 22
n, pcs 8 8 12 12 16
Weight, kg, max 85
KDS-3000 drawing Criteria KDS-3000/250 KDS-3000/350 KDS-3000/500
Breathing combination valve KDS-3000 drawing Diameter Nominal DN 250 350 500
Pressure, Pa (mm w.g.) 2000 (200)
Vacuum, Pa (mm w.g.) 250(25)
Actuation pressure, Pa (mm w.g.) 1500-1600 (150-160)
Actuation vacuum, Pa (mm w.g.) 100-150 (10-15)
Throughput capacity, m3/h 1100 2400 3000
Area of seat passage, sm2 1880
Area of vacuum seat passage, sm2 3760
Overall dimensions, mm, max:  
-length 1300
-width B 1300
-height H 1100 1170 1060
Connection sizes, mm D 370 485 640
D1 335 445 600
d 18 22 22
n, pcs 12 12 16
Weight, kg, max 140

Technical description of the combination mechanical breathing valve SMDK

SMDK valves are used with vertical tanks to compensate pressure fluctuation during filling/unloading or emptying or changing of thermal operational mode. They should be installed strictly in accordance with the volume of inlet — distribution operations.

The design of the SMDK includes fire-stop assembly, which prevents the flame or nucleus of flame penetration. To prevent small particles and dust ingress on the surface of the liquid, a filtering mesh is provided. Mounting is flange through the tightening, which ensures interface integrity.

SMDK valves are manufactured in climatic categories N and NF, placement category 1.

The specified service life is 15 years, after which it is recommended to replace or test it.

SMDK valve drawing Criteria SMDK-50АА SMDK-100АА SMDK-150 SMDK-200 SMDK-250
Combination mechanical breathing valve drawing Diameter Nominal DN 50 100 150 200 250
Throughput capacity, m3/h 25-50 25-100 25-150 25-200 25-250
Overall dimensions, mm, max:
length 285 430 546 740 946
width 122 180 231 340 370
height 202 280 350 320 506
Actuation pressure, mm w.g. 160-180 160-180 160-180 140-160 140-160
Actuation vacuum, mm w.g. 20-25 20-25 20-25 20-25 20-25
Weight, kg 5,5 13 22 47 94

Technical description of breathing enclosed valve KDZT

Breathing enclosed valves KDZT are installed on the roof of the vertical tank on the mount nozzle. They perform the function of pressure control in the gas space during loading-unloading operations or fluid temperature change.

They are produced in climatic categories N and NF, placement category 1. The specified service life is 15 years. When this period is achieved, it is recommended to replace it with throughout capacity recalculation, depending on the loading-unloading operations, or to conduct testing.

KDZT valve drawing Criteria KDZT-50А KDZT-100А KDZT-150А

 

Breathing enclosed valve drawing

 

 

Outline drawing of breathing enclosed valve

 

Diameter Nominal DN 50 100 150
Pressure, Pa (mm w.g.), max 1000 (100) 2000 (200)
Vacuum, Pa (mm w.g.), max 250 (25) 250 ± 20 (25 ± 2)
Actuation pressure, Pa (mm w.g.) 850 ± 50 (85 ± 5) 2500 ± 20 (250 ± 2)
Actuation vacuum, Pa (mm w.g.) 100 - 150 (10 - 15) 250 ± 20 (25 ± 2)
Throughput capacity, m3/h, max 22 120 200
Overall dimensions, mm, max: В,D,H (length, width, height) 170х145х176 350х310х300 450х400х 400
Connection sizes, mm, max D1,d,n 110х14х4 170х18х4 225х18х4
Weight, kg, max 3.5 16 25

Technical description of mechanical breathing valve KDM

Mechanical valves KDM are used with vertical tanks for pressure control of the gas space in the process of loading-unloading operations and working temperature variation. They are supplied together with a flame arrestor, which protects the equipment from fire and explosion dangerous situations by arresting and extinguishing the heat from the fire.

The Saratov Reservoir Plant offers two sizes of valves KDM: KDM-50 and KDM-200. The throughout capacity of the first - 22 m3/h, the second - 150-250 m3/h.

KDM valves are manufactured in climatic categories N and NF, placement category 1. The specified service life is 15 years. At the end of this period, it is required to replace or conduct its testing, taking into account the volume of filling/unloading operations.

KDM-50 drawing KDM-200 drawing
Mechanical breathing valve drawing Mechanical breathing valve KDM-200 drawing
Criteria KDM-50 KDM-200
KDM-200/100 KDM-200/150 KDM-200/200 KDM-200/250
Diameter Nominal DN, mm 50 100      
Pressure, max 2000 Pa
Vacuum, max 250 Pa
Actuation pressure, Pa (mm w.g.), max 1400 Pa 1350-1450
Actuation vacuum, Pa (mm w.g.), max 100-150 Pa
Throughput capacity, m3/h, max 22 150 200 220 250
Length L, mm 328 546
Width В, mm 172 500
Height Н, mm 240 600 650 600 615
Attachment flange diameter D, mm 140 250 260 315 370
On center D1, mm 110 170 225 280 335
Fixing hole diameter d, mm 14 18
Number of Fixing holes n, pcs 4 4 8 12
Weight, kg, max 8 19.2 19.3 19.6 20

Product specification of impermeable breathing valve NDCM

NDKM valves are impermeable membrane breathing valves that are installed on the mount nozzle of vertical tanks operated up to 0.07 MPa. Their purpose is a timely connection of the gas space of the tank with the atmosphere in the process of filling/unloading processes or temperature fluctuations. This is necessary to prevent explosive situations resulting from changes in inner pressure. The design provides a fire safety, which protects the stored liquid from the flame in the gas space. Its mode of action is based on the movement of pressure and vacuum plates.

Impermeable breathing valves are manufactured in climatic categories N and placement category 1.

NDKM valve drawing Criteria NDKM-100 NDKM -150 NDKM -200 NDKM-250
Impermeable breathing valve drawing Diameter nominal of fitting, mm DT 100 mm 150 mm 200 mm 250 mm
Actuation pressure 1372-1569 Pa 1569-1667 Pa
Actuation vacuum 157-196 Pa 177-198 Pa
Throughput capacity, m3/h 200 500 900 1500
Length L, mm 300 510 510 610
Height Н, mm 600 690 670 900
On center D1, mm 170 225 280 335
Fixing hole diameter d 18 mm
Number of Fixing holes n, pcs 8
Weight, kg, max 25 50 55 77

Design and function of breathing valves with a hydraulic gate KPG

They are used as safety valves and are installed together with mechanical breathing valves for additional protection. The principle of action is as follows: in case of pressure increase in the gas space (more than 0.02 kPa, or 5-10%) the latching liquid (oil) is expelled under the pressure, the hydraulic gate is closed and prevents the operating medium from flowing out the tank. In case of vacuum failure, the valve prevents atmospheric air from entering the tank.

It is recommended to install the hydraulic breathing valves in the horizontal orientation: the fluid in the valve may affect the operating value.

They are manufactured in climatic categories N, NF, TA, TH, placement category 1. For operation in cold climates, the moving valve rod and sealants are covered with a fluoroplastic coating that prevents from icing on the surfaces.

Specified service life of the KPG valves is 10 years. At the end of the period, it is required to replace the valve or to conduct preventive measures. For reliable operation, it is recommended to carry out a maintenance control of the oil condition and amount.

Technical specifications of relief hydraulic valves KPG

Relief hydraulic valves KPG drawing  Criteria KPG–100 KPG–150 KPG–200 KPG–250 KPG–350
Relief hydraulic valve drawing Diameter nominal of fitting, mm 100 150 200 250 350
Actuation pressure, Pa (mm w.g.), max 1961 (200)
Actuation vacuum, Pa (mm w.g.), max 392 (40)
Throughput capacity, m3/h, max 200 500 900 1500 2700
Volume of sealing fluid (transformer fluid), l, max 15 22 46,5
Overall dimensions, mm, max:
length L 980 980 1085 1180
width В 845 845 960 1030
height H 1278 1295 1370 1510
Connection sizes, mm, max:
D 205 260 315 370 485
D1 170 225 280 335 445
d 18 18 18 18 22
n 4 8 8 12 12
Weight, kg, max 126 130 134 245 265

Breathing valves design

The following parameters are taken into account for the correct operation of mechanical and hydraulic breathing valves:

  • height above the tank
  • pressure
  • operating temperature

How to buy a breathing valve at our Plant?

The general quantities of the breathing valve is its throughput capacity and set pressure. To buy the tank's breathing valve, You can:

  • call the Plant at +7(8452)250-288
  • send an e-mail  with operating requirements and operating conditions
  • use the form "Request for quotation"

 

See also:

Breather valvesSamplersTank hatches
Bottom cleanout boxesNozzles, nipples, connecting pipes, fittingsFlame arresters
Tank clap valves