Kevin Prokopius and Anthony Colozza 

Analex Corporation, Cleveland, Ohio

High Pressure Electrolyzer System Evaluation

NASA/CR—2010-216110

February 2010
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Kevin Prokopius and Anthony Colozza 

Analex Corporation, Cleveland, Ohio

High Pressure Electrolyzer System Evaluation

NASA/CR—2010-216110

February 2010

National Aeronautics and

Space Administration

Glenn Research Center

Cleveland, Ohio 44135

Prepared under Contract NAS302150–100
Available from

NASA Center for Aerospace Information

7115 Standard Drive

Hanover, MD 21076–1320

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Level of Review: This material has been technically reviewed by expert reviewer(s).
NASA/CR—2010-216110 1 

High Pressure Electrolyzer System Evaluation 

Kevin Prokopius and Anthony Colozza 

Analex Corporation 

Cleveland, Ohio 44135 

Abstract 

This report documents the continuing efforts to evaluate the operational state of a high pressure PEM 

based electrolyzer located at the NASA Glenn Research Center. This electrolyzer is a prototype system 

built by General Electric and refurbished by Hamilton Standard (now named Hamilton Sunstrand). It is 

capable of producing hydrogen and oxygen at an output pressure of 3000 psi. The electrolyzer has been in 

storage for a number of years. Evaluation and testing was performed to determine the state of the 

electrolyzer and provide an estimate of the cost for refurbishment. Pressure testing was performed using 

nitrogen gas through the oxygen ports to ascertain the status of the internal membranes and seals. It was 

determined that the integrity of the electrolyzer stack was good as there were no appreciable leaks in the 

membranes or seals within the stack. In addition to the integrity testing, an itemized list and part cost 

estimate was produced for the components of the electrolyzer system. An evaluation of the system’s 

present state and an estimate of the cost to bring it back to operational status was also produced. 

Electrolyzer Stack Evaluation 

This section summarizes the evaluation and testing of the Hamilton Standard high-pressure 

electrolyzer originally documented in the report titled “Hydrogen Generation through Renewable Energy 

Sources at the NASA Glenn Research Center” (Ref. 1). This evaluation consisted of a nitrogen pressure 

test of the electrolyzer stack to determine with greater detail the integrity of the stack membranes. 

Previous evaluation (described in Ref. 1) of the electrolyzer stack consisted of hydrating the stack by 

providing a deionized water feed to the stack through the water inlet port. From this initial evaluation it 

was concluded that the Hamilton Standard electrolyzer stack’s membranes were completely hydrated and 

there appeared to be water leakage from the stack to the pressure chamber that housed the stack. Checkout 

of the stack over the 41⁄2 months prior to completion of the final report (Ref. 1) in May 2006 led to these 

conclusions. Since May 2006, there were periodic checks on the water level in the stack over the 

following 6 months. Table 1 provides volumes of deionized water added at certain times throughout the 

year through December 2006. 

The collected data on the volume of water added to the electrolyzer was surprisingly encouraging 

with the exception of the last reading. Quantities of water added to the electrolyzer have leveled off and 

began to decrease somewhat. This can be seen from the last column in Table 1. This perhaps indicates the 

stack’s membranes are hydrated and the loss is due to evaporation, whose rate will be weather related. 

The last volume of water added to the electrolyzer on December 15, 2006, was submitted just prior to 

performing the pressure test on the unit. The reason for the added water volume per day increase shown in 

the last data point is not completely clear. The volume added for this last data point is approximate due to 

an error in measurement. This approximation of the volume or the lower humidity in December could be 

the cause of the higher mL/day rate for this last data point. 

The purpose of the electrolyzer pressure test with nitrogen gas was to verify the stack condition and 

or the extent of leakage. The electrolyzer is normally filled with deionized water on the oxygen side of the 

stack so the pressure test will quantify leak rates to either the hydrogen side of the stack or directly into 

the pressure chamber. The ability for the stack to maintain pressure or the leak rate will provide a 

 
NASA/CR—2010-216110 2 

detailed assessment of the integrity of the seals on the stack. If pressure is maintained this indicates that 

the seals and cell membranes are intact. Or if a leak is detected this indicates a failure of one or more seals 

and or membranes within the stack. The rate of leakage (pressure drop) will give an indication of the 

severity of the failures. However, any rapid pressure drop of the gas represents an internal failure within 

the stack. 

TABLE 1.—VOLUME OF DEIONIZED WATER ADDED 

TO THE ELECTROLYZER STACK SINCE MAY 2006 

Date Volume 

(mL) 

mL/Day 

June 12, 2006 45 N/A 

June 21, 2006 13 1.44 

June 29, 2006 10 1.25 

July 10, 2006 30 2.72 

August 11, 2006 7 0.22 

November 11, 2006 113 1.09 

December 15, 2006 ~100 4.16 

Electrolyzer Stack Testing Procedure

The pressure test of the electrolyzer stack was performed on December 15, 2006, using high purity 

nitrogen gas over a range of pressures to provide a top level indication as to the stack’s condition. For the 

testing, the nitrogen gas pressure was increased up to a level just below 30 psig. A relief valve, set at 

30 psig, was used to ensure that this maximum pressure level was not exceeded. Figure 1 captures the 

individual tests performed on the stack. The first step was to remove the deionized water from the stack 

by opening all gas ports (nitrogen, oxygen, hydrogen) and then supplying nitrogen gas at 5 psig into the 

distilled water feed line. This pressurized gas forced the majority of the deionized water out of the stack. 

Each of the gas ports have been identified in the schematic (Fig. 1) along with the appropriate SSP fitting 

used to perform the outlined tasks. 

After removing the contained deionized water from the stack, the next step was to pressurize the 

oxygen side of the stack with nitrogen to see if the gas passed onto the hydrogen side, which would 

indicate a leak in either a seal or membrane. The nitrogen pressure was adjusted in 5 psig intervals up to a 

supply pressure of 29 psig. At 25 psig, the cap was removed off the nitrogen port (8) to simultaneously 

check for leaks into the pressure chamber. After performing the oxygen side pressure testing, it was 

decided to confirm the electrolyzer’s normal mode of operation of being fed distilled water on the oxygen 

side of the stack. This was accomplished by capping the hydrogen port (6), opening the oxygen port (1), 

and applying 5 psig of nitrogen to the system through the water inlet port. The valve directly on the 

nitrogen k-bottle was closed and the pressure was seen to drop immediately in the supply line confirming 

water feed to the oxygen side. 

The final step in the test procedure was to pressurize the oxygen side with nitrogen to see if leaks 

occurred directly into the chamber. The nitrogen pressure was adjusted in the same manner as performed 

earlier (5 psig intervals up to 29 psig). 

After performing this final checkout test, the nitrogen test assembly was removed and all liquid/gas 

ports were capped except for ports 1 and 6 located on the pressure chamber. This was done to allow for 

evaporation of trace amounts of water from the stack pressure chamber prior to storage. These ports were 

left open for 1 week and then capped on December 22, 2006, to keep the pressure chamber free of 

contaminants. 
Figure 1.—Individual electrolyzer stack checkout steps. 

NASA/CR—2010-216110 3 
NASA/CR—2010-216110 4 

Electrolyzer Stack Test Results and Conclusions 

During the water removal procedure (Step 1), most of the water was seen to blow out of the oxygen 

port at 5 psig. A small amount was seen to remain behind as it fell back by gravity down the oxygen port 

into the stack. Due to the pressurized nitrogen gas flow, the water within the stack abruptly shot into the 

air and was not able to be captured for measurement. 

The first nitrogen leak test from the oxygen to the hydrogen side of the stack resulted in no observed 

pressure drop at supply pressures of 5, 10, 15 and 20 psig. The nitrogen pressure held at each interval for 

approximately 2 min. At 25 psig, nitrogen port 8 at the bottom of the vessel was opened and the pressure 

was seen to hold steady for about 5 min confirming no major leaks to either the hydrogen side of the stack 

or into the chamber. Port 8 was kept open and the pressure was increased to 29 psig. After 10 min had 

elapsed, the pressure was seen to drop to only 28 psig. Overall, after a total of 20 min of elapsed time, the 

pressure dropped to only 27 psig. 

The second leak test from the oxygen side of the stack to the pressure chamber similarly resulted in 

no observed pressure drop at supply pressures of 5, 10, 15, 20 and 25 psig. The nitrogen pressure was 

held at each interval for roughly 2 min except at 25 psig where the stack held at pressure for about 4 min. 

The pressure was then increased to 29 psig and after 10 min had elapsed, the pressure was seen to drop to 

only 28.5 psig. The stack remained at 28.5 psig for another 5 min before the checkout was terminated. 

Both tests indicate that there is no major defect with the stack. The observed 2 psig drop during the 

first test was due to the membrane’s permeability and perhaps very minute leaks at the electrolyzer’s 

fittings. The water level in hydrogen port 6 rose slightly during the first test confirming the membrane’s 

permeability. 

A torn membrane or a ruptured/cracked seal would have resulted in a very rapid drop in pressure, 

even at low supply pressures such as 5 psig. Since this type of event did not occur during the oxygen side 

to hydrogen side pressure testing, it can be concluded with a high degree of certainty that the high 

pressure electrolyzer stack is in good condition and free from any appreciable leaks due to membrane or 

seal failure. 

Evaluation of the State of the Electrolyzer System 

The purpose of this evaluation is to identify the components and/or systems (other than the actual 

stack) that will need to be refurbished or replaced. A visual inspection was performed on the electrolyzer 

system, noting most of the significant components that make up the balance of plant. Overall the state of 

the electrolyzer system components was fairly poor. The majority of the system will need to be replaced 

and due to the age of the system and the compatibility of the components installed with commercially 

available newer components, it may be more cost beneficial to completely rebuild the fluid and control 

systems than to try and salvage any of the components. 

There are a number of open lines and severed electrical connections that would need to be completely 

replaced. The open lines are of particular concern since the cleanliness of the system is critical to the 

operation of the electrolyzer stack and with the use of oxygen in the process lines. Figures 2 through 7 

provide examples of the present state of the system components. 

The above figures show an example of the state of the system’s mechanical and electrical 

components. Although some components may be salvageable, it is recommended that the system be 

completely rebuilt utilizing the electrolyzer stack and containment vessel. The containment vessel was 

sealed off from the fluid lines and therefore should be contaminant free and based on the results of the 

pressure testing the stack should be in good operational condition. Table 2 gives a summary of the 

estimated replacement cost for most of the major system components. 
NASA/CR—2010-216110 5 

Figure 2.—System cabinet. 

Figure 3.—Electrolyzer system cabinet base. 
NASA/CR—2010-216110 6 

Figure 4.—Cut power and data cable interfaces. 

Figure 5.—Disconnected internal components. 
NASA/CR—2010-216110 7 

Figure 6.—Electrolyzer stack pressure vessel with disconnected fluid lines. 

Figure 7.—Disconnected internal fluid lines. 
NASA/CR—2010-216110 8 

TABLE 2.—ELECTROLYZER SYSTEM COMPONENT COST SUMMARY 

Component type Manufacturer Part number Quantity Total estimate 

replacement cost 

Normally Closed Actuated Valve Nupro SS-HBS6-C 5 $1,616 

Normally Open Actuated Valve Nupro SS-HBS6-O 3 $970 

Back Pressure Regulator Not Available Not Available 2 $1,600 

Circulation Pump Midland Ross 970P100 1 $1,100 

Check Valve Not Available Not Available 10 $650 

Differential Back Pressure Regulator General Electric Not Available 1 $800 

Differential Back Pressure Regulator Tescom 269-403 2 $1,600 

Differential Back Pressure Regulator Tescom 269-454-2 1 $800 

Differential Back Pressure Regulator Tescom 269-402 1 $800 

Differential Pressure Regulator General Electric Not Available 2 $1,600 

Differential Pressure Transducer Shaevitz 

Viatran 

P2194-001 

220-15 

 3 

 1 

 $2,250 

 $750 

Electronic Control Valve Hewlett Packard Not Available 3 $3,315 

Filter Not Available Not Available 6 $300 

Rotameter Fischer & Porter 10A3135 3 $450 

Feed Pump March Mfg. Co. TE-7R-MD 1 $1,200 

Gas Analyzer Control Inst. B7SNR006 3 $6,000 

Heat Exchanger Not Available Not Available 1 $750 

Hydrogen Phase Separator Not Available Not Available 2 $7,000 

Heater Not Available Not Available 1 $900 

Level Switch IMO Delaval Not Available 3 $590 

Oxygen Phase Separator Not Available Not Available 1 $8,000 

Orifice Not Available Not Available 8 $160 

Pressure Gauge Not Available Not Available 7 $420 

Pressure Regulator Not Available Not Available 3 $2,400 

Pressure Switch Kratos 50820 1 $75 

Pressure Transducer Shaevitz P793-001 5 $3,750 

Resistivity Sensor Foxboro CEL-272 3 $1,275 

Temperature Sensor RdF 21SP-A-10 4 $360 

Relief Valve Circle Seal P13-485 7 $840 

Solenoid Valve Asco Not Available 15 $1,800 

Manual Valve Circle Seal, Hoke Not Available 21 $4,850 

Venturi Not Available Not Available 1 $125 

Resistivity Monitor Foxboro 874RS-AT 1 $300 

DH-485 PC Interface Allen Bradley 1747-KE 1 $600 

TOTAL $45460 

The electrolyzer system can be refurbished in house at NASA Glenn or returned to the manufacturer 

for complete refurbishment. The majority of the cost for rebuilding the electrolyzer in-house will be in 

technician and engineering time. Without being able to evaluate the electrolyzer stack in detail, the 

manufacturer cannot provide a detailed cost estimate for its refurbishment. However, based on previous 

system work an estimate of the refurbishment cost and or labor hours can be made. These are given in 

Table 3. 

TABLE 3.—ELECTROLYZER SYSTEM REFURBISHMENT COST ESTIMATE 

 Estimated manufacturer refurbishment In-house refurbishment 

Estimated cost or labor hours $435,000 labor 

 $ 65,000 parts 

320 engineering hours 

400 technician hours plus hardware costs 
NASA/CR—2010-216110 9 

Should a program arise to use the electrolyzer system, the recommendation would be to have 

Hamilton Standard aka Hamilton Sundstrand refurbish the system. Hamilton Sundstrand would come onsite to perform a complete, detailed analysis of the stack’s integrity and quote an actual refurbishment 

cost based on their observations and findings. Their prior working knowledge of the overall system is 

invaluable and the refurbishment cost will most likely be lower than having the work performed in-house. 

References 

1. Colozza, A.J. and Prokopius, K., “Hydrogen Generation through Renewable Energy Sources at the 

NASA Glenn Research Center”, NASA/CR 2007-214682, April 2007. 
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High Pressure Electrolyzer System Evaluation 

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14. ABSTRACT

This report documents the continuing efforts to evaluate the operational state of a high pressure PEM based electrolyzer located at the 

NASA Glenn Research Center. This electrolyzer is a prototype system built by General Electric and refurbished by Hamilton Standard (now 

named Hamilton Sunstrand). It is capable of producing hydrogen and oxygen at an output pressure of 3000 psi. The electrolyzer has been in 

storage for a number of years. Evaluation and testing was performed to determine the state of the electrolyzer and provide an estimate of the 

cost for refurbishment. Pressure testing was performed using nitrogen gas through the oxygen ports to ascertain the status of the internal 

membranes and seals. It was determined that the integrity of the electrolyzer stack was good as there were no appreciable leaks in the 

membranes or seals within the stack. In addition to the integrity testing, an itemized list and part cost estimate was produced for the 

components of the electrolyzer system. An evaluation of the system’s present state and an estimate of the cost to bring it back to operational 

status was also produced. 

15. SUBJECT TERMS

Electrolysis; Hydrogen production; Oxygen production 

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