Equalization valves with bellows

Our equalization valve did not have a bellows attached, and worked extremely well during the testing period. However, a bellows should be considered a necessary addition to prevent leakage of hydrogen, and to isolate the hydrogen stream from possible contaminants that arise from the cylinder lubricant/seal used. 

Stainless steel stock bellows can be purchased from the suppliers listed. Inquire what type of necks are available in stock 

Very few parts are necessary to construct this valve  

After the holes are drilled and the rod is threaded, simply screw the standoff onto the threaded piston rod after applying a little silicone or epoxy glue. Punch a 34 diameter silicone rubber disk from a 3/32n thick piece and glue this onto the end of the standoff. This is the gasket-seal for the oxygen outlet. 

This is only one particular design among many that can be used and no doubt many improvements can be made on this particular design. 

---

Figure 11.26 shows a system in which compressed gas recycles fr om the discharge, upstream of the shutoff valve, to the inlet of the suction chiller. Passing the recycled gas through the suction chiller (or other precooler) cools the gas so that the control valve can handle the full compressor capacity. The control valve is a fail-open globe valve with an equal percentage characteristic and a positioner. It should be sized to handle full compressor output when 90% open. The valve seal can be a Monel bellows or a Hastelloy C stem with double PTFE packing. 

For the main fuel drain circuit, bellows-sealed, mechanically operated, poppet alves (.see Section 15-3) will be placed in scries with the freeze valves to establish a stagnant licjuid suitable for freezing. Normally these mechanical valves will be left open. By melting the plug in the freeze line and opening gas-equalization valves, the liquid in the reactor will flow by gravity to the drain tank, and the gas in the drain tank will be transferred to the reactor system. Thus gas will not have to be added to, or vented from, the primary system. 

An in-line pH control system is installed when the brine is to be acidified. HCl is added upstream of an inline mixer, with measurement downstream of the mixer. This is a simple case of pH control, the end point being fairly low. The process gain is also low in this case, and control is easier than in the first stage of the pH adjustment, described in the previous section. The acid valve should be a fail-closed globe valve of equal percentage characteristic with full PTFE lining and FIFE bellows. An interlock should close the acid feed valve whenever there is no brine flow or no current on the cells. 

---