TP12100M – TANK BLANKETING SYSTEM – 1” & 2” (DN25 & DN50)
Blanketing of medium and large tanks
Lower maintenance costs due to fewer parts
Inexpensive replacement parts
Standard valve material provides added corrosion protection at no additional cost
Valve design ensures integrity and protects against injury to personnel
Bubble tight at set point prevents waste of blanketing gases
Single valve system
Compact & light weight
Supply pressure fl uctuations do not affect set point
Uses standard o-rings
Top entry design for easy maintenance
Set points from vacuum to 14 psig
Self cleaning fl ow design of main valve and pilot
Temperature changes have no appreciable effect on set point
1″ & 2″ FNPT (screwed)
1″ & 2″ 150# & 300# RF threaded fl anges with nipples
1″ & 2″ 150# & 300# RF weldneck fl anges
DN25 (PN40) & DN50 (PN40) weldneck flanges
Any combination of above
Larger size reducing fl anges are available on request.
Horizontal or Vertical Valves with FNPT or nipple and threaded flange connections can be confi gured in the field. Valves with weldneck fl ange connections, confi guration must be specified at time of order.
Remote sensing Integral diptube sensing
Minimum: 20 psig (1.83 Bar)
Maximum: 200 psig (13.83 Bar)
See Table 6
OUTLET PRESSURE RANGES
See Table 3
MAXIMUM BACK PRESSURES
25 psig (1.7 Bar) – standard
Higher pressures on request
MATERIALS OF CONSTRUCTION
Body Material: 316 SST
Carbon Steel (only available on 2″)
Diaphragm Case Material: Carbon Steel / 316 SST
Trim Material: 316 SST
Diaphragm Material: Teflon®
Soft Seat & Seals: Fluorocarbon Elastomer – standard, Buna-N, Chemraz®, EPDM or Kalrez®
On request elastomers to FDA requirements
Fluorocarbon Elastomer – (FKM) 0° to 212° F (-17° to 100° C)
Buna-N (Nitrile-NBR): -40° F to 180° F (-40° C to 82° C)
EPDM (Ethylenepropylene): -50° F to 212° F (-45° C to 100° C)
Chemraz® (Perfl uoroelastomer-FFKM): 0° F to 212° F (-18° C to 100° C)
Kalrez® (Perfl uoroelastomer-FFKM): 0° to 212° F (-18° to 100° C)
1″ Model 9890 FNPT: 18 lbs (8.2 kg)
2″ Model 9890 FNPT: 43 lbs (20 kg)
1″ Model 9890 Flanged: 23 lbs (10.5 kg)
2″ Model 9890 Flanged: 55 lbs (25 kg)
The capacity requirement of the tank blanketing valve is the sum of two components. The first being inbreathing due to liquid or product movement out of the tank and the second being inbreathing due to contraction of the vapors/product because of weather changes.
Inbreathing due to maximum liquid or product movement out of the tank equals 8.0 SCFH of air for each US gallon per minute of maximum emptying rate or 0.94 Nm3/h of air for each m3/h of maximum emptying rate.
Q displacement (SCFH) = Max. Pumpout Rate (gpm) x 8.0
Q displacement (Nm3/h) = Max. Pumpout Rate (m3/h) x .94
The second component, inbreathing due to weather changes, is selected from Table 5 (Table 5A). The tank capacity is found in column 1 and the corresponding inbreathing requirement is selected from column 2.
The two components are added together to give the total inbreathing requirement and the capacity requirement of the tank blanketing valve.
Q total = Q displacement + Q thermal
If the tank blanketing supply pressure varies, use the minimum supply pressure in selecting the tank blanketing valve and the maximum supply pressure to determine blanketing valve failure capacity. Using the minimum supply pressure select the size valve from Table 6 that will meet the Total Inbreathing Requirement (Q total). Next determine if a reducing “fl ow plug” can be used to make the capacity of the tank blanketing valve more closely match the inbreathing requirements. This will also reduce the fail open capacity of the blanketing valve. This is done by dividing the required inbreathing (Q total) by the full capacity of the size valve selected and multiplying by 100. Now from Table 2 choose the fl ow plug that isgreater than the calculated percentage.
Figure 1 shows the AKTEK-NBV® in the closed position. This occurs when the tank pressure satisfi es or exceeds the set pressure of the pilot. When the sensed pressure is suffi cient to overcome the downward force of the set pressure spring, the pilot will close and there is no fl ow out of the pilot. This causes full supply pressure to accumulate in the chamber above the main valve piston. Since the piston area is larger than the seat area at the lower end of the piston, when the pressure above the piston is equal to the supply pressure the piston will move downward to close the valve due to the presence of a higher downward force.
Figure 2 shows the AKTEK-NBV® in the open position. When the tank pressure, that is sensed in the sense chamber below the diaphragm, is insuffi cient to hold against the downward force of the set pressure spring, the spindle in the pilot chamber will be forced downward. As the spindle unseats, the pressure in the pilot chamber will be discharged into the outlet of the valve. A small orifi ce restricts the gas fl ow into the pilot chamber from the supply pressure. Therefore, as soon as the pilot spindle opens, the pilot chamber pressure will drop signifi cantly and will not be able to hold the main valve piston down. The piston will now be pushed full open by the supply pressure, allowing a maximum fl ow of the blanketing gas into the tank. Once the tank pressure is back to set point, the spindle will close and the pilot pressure will rise to full supply pressure, pushing the main valve piston back down into the fully closed position.