Air Valves Head Office : İşçiler Caddesi No: 124 Yenişehir / İZMİR-TURKEY Phone: (pbx)

Transcription

1 Air Valves Head Office : İşçiler Caddesi No: 124 Yenişehir / İZMİRTURKEY Phone: (pbx) Fax: Branch : 1203/4 Sokak No: 1/C Yenişehir / İZMİRTURKEY Phone: Factory : Mehmet Akif Ersoy Mahallesi 1. Öteyaka Mevkii No: 40 Kemalpaşa / İZMİRTURKEY Phone: (pbx) Fax:

2 DESCRIPTION and TECHNICAL Air Valves General : What is an Air Valve? : An air valve is a valve mounted in TEE configuration on a pipeline to discharge or admit air into or out of the pipeline. Why should the air in the pipeline to be controlled? : The existence of trapped air in a pipeline under pressure can cause negative effects on system operation and efficiency. Air pockets accumulating at slope sign changing high points reduce the effective crosssection of the pipeline in the location of accumulation, which causes a decrease in the flow rate, and the energy needed to pressurize the waterflow is increased. The overall system efficiency is then reduced. Air pockets beyond some critical quantity in the system even may restrict the whole pipeline from flowing, locking the pipeline. Sources of Air in Water Pipelines The existence of air in a pipeline might be because : Air under atmospheric conditions might stay within the pipeline when the pipeline was filled with water. With the absence of air discharge valves, accumulation of air occur at local high points. Water at normal conditions, pressure (1,325 kpa) and temperature (25 C), contains approximately 2% (by volume) of dissolved air. Due to the terrain slopes, variations in flow velocity caused by changing pipe diameters, partiallyopen valves, etc. the water flow is subjected to changing pressures and temperatures, and the dissolved air may be released from the water mass, forming into gas, accumulating as air pockets in the local peak points. Air may be drawn into the pipeline at startup of deepwell pumps, and through leaking joints at zones above the hydraulic gradients (negative pressure points). Air can also be admitted into the system by air valves operating on belowatmospheric pressures. Double Chamber Design Pattern The Types and Functions of AirValves: a Kinetic Air / Vacuum Valves (Double Acting or Single Orifice Valve): Venting/Kinetic airrelease function: Exhaust large quantities of air from the pipeline when it is filled with water, at low pipeline pressure. Vacuum Breaking/Kinetic antivacuum function: Admit large quantities of air into the pipe when it is drained, or when the internal pressure drops below atmospheric pressure due to transient conditions. b Automatic Air Release Valves: Releasing small pockets of accumulated air while the pipeline operates under pressure ( Automatic airrelease function) c Combination Air Valves (Triple Acting or Double orifice valve) : A valve that performs the functions of both the Kinetic and Automatic operations. d Additional Feature NonSlam or Antishock Operation (Four Action or Triple Orifice Valve): A valve that senses the excessive air discharge and so the water approach velocity and reducing the air discharge velocity by intensionally sucking the nonslam float upwards but continuing to discharge at some lower rate inducing an air cushion in the pipeline. This function causes the waterflow to pass the critical point slowly and prevents the impact or surge inducing wet close of the air valve. 2

3 DESCRIPTION and TECHNICAL Air Valve Capacity and Sizing : Air Valve sizing depends several criteria on at what pressure difference the valve will operate and what consequences will arise at this operating criterion. The criteria are summarized as below : Design for Vacuum : Criterion 1 : Full opening of a discharge valve to empty the pipeline at the and of a V, with maximum static pressure. Critical Vacuum Condition. Single Chamber Design Pattern Criterion 2 : Having the same geometry of Criterion 1 with a pipe burst opening equal to nominal pipe size at the maximum static pressure condition. The valve at the beginnig of upslope should have enough capacitiy to admit enough air into the pipeline to replace the downgoing column to overcome vacuum and collapse. Design capacity only for vacuum according to these preceding two criteria suggest the limit for choking on design. On choking condition the limiting value DeltaP of 0,528 bar ( ~ 53 kpa), suggests no remarkable change beyond ~ 0,35 bar. To stay on the safe side, The value 0,2 bar DeltaP should not be exceeded. On an Emptying/Filling Rate of 2:1 for pipeline design, This value is to be limited down to 0,,15 bar. However, even if this value suggests proper operation away from the collapse limit of pipe line, the vacuum will admit unwanted foreign objects causing contamination in the pipe line. So this limiting value for design is outofdate as per the design criteria. Design for Discharge : Criterion 3 : When filling the pipeline, choosing a Pressure Differential of 0,,15 bar for discharge of air. Air flow velocity at this point of operaiton will exceed 124 m/s. However, capacitywise being good suggested by the former criteria, this value is tremendously high to induce impact on wetclosing of the valve upon arrival of water to point. On nonkinetic designs, this value of air velocity will induce a venturieffect to suck the float closing prematurely, blocking the flow out. The air stays trappred and there is no possibility that the valve opens as the pressure accumulation pushes the float further to close. On kinetic designs, the floats will not be affected from the venturieffect, and the air flow will continue until wetclosing. However, the tests and experience for the last decades show that wetclosing at this discharge velocity induces Surge, which implies local pipe bursts. Most of the pipe bursts occur from uncontrolled filling rates and/or wrong selection or mislocation of air valves on pipe line design. Result : Design of an air valve on limiting capacity for protection from vacuum is not a proper approach. Vast experience on last decades shows, local discharge of air beyond 0,05 0,07 bar DeltaP will induce unbearable surge in the pipeline. This DeltaP suggests an effective discharge velocity of 3035 m/s of air a t the uppermost orifice of the air valve. Beyond this limiting value it is suggested that the opertion of the pipelinefilling is refrained. This limiting air discharge condition is also used for the design of the antishock or nonslam orifices. Design on capacity curves given on manufacturers is necessary, but not sufficient. The designer should follow the limiting criteria on field of operation. On most critical operation, the selection of the air valve should depend on pipe line filling rate. The curves are as in page CAPACITY CURVES 3

4 H H AIR VALVES DIMENSIONS and WEIGHTS L DOUBLE CHAMBER AIR VALVE 3 EFFECT, KINETIC AUTOMATIC COMBINATION ( Air Discharge, Air Intake, Air Release ) This type of air valve is the newgeneration design for the wellknown double chamber air valve. The 3 functions of traditional double chamber design is conserved, combining thermoplastic cylindrical shaped main float for air intake and air discharge fuctions with the stainless steel float for air release function. This gives an advantage on longterm corrosion resistance and longer operatinal lifetime compared to the competitors designs in the market. Functions: 1. Discharge of air in high volume in the pipeline to atmosphere during pipe filling. ( Atmospheric Function) 2. Intake of air in high volume into the pipe line during pipeline emptying. ( Atmospheric Function ) 3. Discharge of low volumes of air preventing them to accumulate and form airpockets during pipeline operation. ( Pressurized Function ) DN 2 4 SIZE, WEIGHT AND DIMENSIONS, CAPACITY DN (mm) H (mm) L (mm) Weight (Kg.) Capacity (nl/s)* *Capacity is the limited flowrate with Antishock orifice for normal operation L Technical Data: Nominal Size : DN50 DN300 Nominal Pressure : PN 1 25 Flange Standard : TS ISO / TS EN 22 Temperature : C C Coating : Electrostatic Epoxy Powder RAL50 Option : As per order; Body and Cover,, AISI31 Floats Materials: BODY AND COVER EN ASTM UNS DIN DN GREY CAST IRON GG25 DUCTILE CAST IRON DUCTILE CAST IRON GGG50 EN GJL EN GJS40015 EN GJS5007 A4840B A53/040 A53/54512 F F F STEEL CASTING A21WCB J STAINLESS SEEL 304 A351CF8 J STAINLESS STEEL 31 A351CF8M J STAINLESS STEEL DUPLEX DUPLEX 2205 S STAINLESS STEEL SMO254 SMO 254 S NiAl Bronze B148 C FLOATS :, AISI31,, PP 12 STANDARD MATERIALS Body Floats ( Single Chamber ) PRESSURE CLASSES PN/1 PN25 PN40 ANSI150 ANSI300 ANSI00 HP PP Floats ( Double Chamber ) FLANGE DRILLINGS : PN, PN1, PN25, PN40, ANSI150, ANSI300, ANSI00 D N 4

5 H H SINGLE CHAMBER AIR VALVE AIR VALVES DIMENSIONS and WEIGHTS 4 EFFECT, KINETIC AUTOMATIC COMBINATION + ANTISHOCK ( Air Discharge, Air Intake, Air Release + NonSlam Closure) L 1 1 ½ This type of air valve is the new generation design of combination air valve to compansate for the pipeline design and application defects at air discharge criterion. It accomplishes 4 functions in a single chamber rather than the triple funtion in double chamber design, by limiting the air discharge during uncontrolled pipeline filling. Functions: 1. Discharge of air in high volume in the pipeline to atmosphere during pipe filling. ( Atmospheric Function) 2. Intake of air in high volume into the pipe line during pipeline emptying. ( Atmospheric Function ) 3. Discharge of low volumes of air preventing them to accumulate and form airpockets during pipeline operation. ( Pressurized Function ) 4. Limiting of the air flow velocity during disharge when uncontrolled or high velocity pipeline filling. This causes an aircushion in the pipeline, lowering the approach velocity of water running, reducing the risk of induced impact (surge) on reduced speed arrival of water ( wetclosure) of the main float. SIZE, WEIGHT AND DIMENSIONS, CAPACITY DN (mm) H (mm) L (mm) Weight (Kg.) Capacity (nl/s)* D N Technical Data: Nominal Size : DN50 DN300 Nominal Pressure : PN 1 25 Flange Standard : TS ISO / TS EN 22 Temperature : C C *Capacity is the limited flowrate with Antishock orifice for normal operation. 3, Coating : Electrostatic Epoxy Powder RAL50 Option : As per order; Body and Cover,, AISI31 Floats Materials: BODY AND COVER EN ASTM UNS DIN GREY CAST IRON GG25 EN GJL A4840B F DUCTILE CAST IRON EN GJS40015 A53/040 F DN DUCTILE CAST IRON GGG50 STEEL CASTING EN GJS5007 A53/54512 A21WCB F 330 J STAINLESS SEEL 304 A351CF8 J STAINLESS STEEL 31 A351CF8M J STAINLESS STEEL DUPLEX DUPLEX 2205 S STAINLESS STEEL SMO254 SMO 254 S NiAl Bronze B148 C FLOATS :, AISI31,, PP STANDARD MATERIALS PRESSURE CLASSES PN/1 PN25 PN40 ANSI150 ANSI300 ANSI00 Body 12 Floats ( Single Chamber ) Floats ( Double Chamber ) FLANGE DRILLINGS : + + HP + PN, PN1, PN25, PN40, ANSI150, ANSI300, ANSI00 PP DN 5

6 TYPES AND LOCATION Air Valve Location on Pipelines : Hydraulic Gradient Line Long Descent Horizontal Run Long Ascent Kinetic Air Discharge/Vacuum Valve Automatic Air Release Valve Combination Air Valve Pump Check Valve Drain Valve Reservoir Air Valve Location on Pipelines : The recommendation of AWWA steel pipe manual on location of air valves on a pipeline is: 1. High Points Combination Valve (Triple Acting) 2. Long Horizontal Lines Air Release or Combination Valve (intervals of ~400 m.~750 m.) (Triple Acting) 3. Long Ascents Air Vacuum Valve (intervals of ~400 m.~750 m.) (Double Acting) 4. Long Descents Combination Air Valve (intervals of ~400 m.~750 m.) (Triple Acting) 5. Increasing change on downslope of line Combination Air Valve (Triple Acting). Decreasing change in upslope of line Air Vacuum Valve (Double Acting)

7 PERFORMANCE CHARTS Main Orifice Discharge Performance Chart Air Flow Chart Intake and Discharge Rates of Free Air Flow Line Pressure (bar) On the upper orifice Outflow SCFM Air Intake nm³/h Outflow nm³/h nm³/h = normal m³/h SCFM: Standard Cubicfeet per second 8 kpa 20ºC 14. psi 8ºF Intake SCFM Line Pressure (psi) Air Release Orifice Discharge Performance Chart p (bar) Q (scfm) Ø1.2mm(Ø0.047")smallorificeDN25(1")&DN50(2")Valves Ø1.5mm(Ø0.05")smallorificeDN80(3")&DN0(4')Valves Ø2.4mm(Ø0.04")smallorificeDN150(")&DN200(8')Valves Ø3.2mm(Ø0.125")smallorificeDN(")&DN300(12')Valves 5 Q(nl/s) p (psi) 7

8 SIZING TO PIPELINE PIPE SIZEI [ mm.] 2400,0 2300,0 2200,0 20,0 2000,0 0,0 00,0 1700,0 0,0 1500,0 1400,0 1300,0 1200,0 10,0 00,0 00,0 800,0 700,0 00,0 500,0 400,0 300,0 200,0 0,0 0,0 DN 300 mm. DN mm. DN 200 mm. DN 150 mm. DN 125 mm. DN 0 mm. DN 80 mm. DN 50 mm. AIR VALVE SIZING CHART KINETIC, FULL BORE DESIGN 0,5 0,75 1 1,25 1,5 1,75 2 2,25 2,5 2,75 3 PIPE FILLING RATE (max.) [ m/s ] 2400,0 AIR VALVE SIZING CHART TRIPLE EFFECT KINETIC, FULL BORE DESIGN DOUBLE PARALLEL INSTALLATION PIPE SIZE [ mm.] 2300,0 2200,0 20,0 2000,0 0,0 00,0 1700,0 0,0 1500,0 1400,0 1300,0 1200,0 10,0 2 X DN 300 mm. 2 X DN mm. 2 X DN 200 mm. 00,0 0,5 0,75 1 1,25 1,5 1,75 2 2,25 2,5 2,75 3 PIPE FILLING RATE (max.) [ m/s ] 8

9 PARTS LIST ADETAIL Poz No: Product Description Body Cover Bearing Shaft Stop Plate Floater Filter Oring Oring Spring Washer Blind Nut Hexagon Head Spring Washer Hexagon Head Bolt Floater Body Floater Cover Joint Connection Plate Joint Seal Floater Pin Shaft Ring Countersunk Bolt Oring Oring Oring Seal Seal Spring Camshaft Socket Bolt Socket Bolt Bolt Grub Filter Shaft Filter Housing Material Ductile cast iron () Steel (St523) Polyethylene (PE300) Galvanized Steel (8.8) Galvanized Steel Ductile cast iron () Steel (St37) Stainless Steel Vulcanized Rubber Coating Stainless Steel Polyurethane (PU) Polyurethane (PU) Stainless Steel A