COMPRESSED AIR SYSTEM 

REFURBISHMENT AND 

MODERNIZATION

BY

MOIZ BUTT

Reactor Operations and Engineering Group

NIST Center for Neutron Research (NCNR)

Gaithersburg, MD 20899
BACKGROUND

 The compressed air system is 

used for a variety of safety and 

control functions within 

NCNR, and as such, its 

reliability is critical to the safe 

continued operation of the 

National Bureau of Standards 

Reactor(NBSR).

 Critical reactor control and 

support systems include 

components of ventilation, 

confinement doors, storage 

pool, fuel transfer system, and 

other integral systems. 
PROJECT APPROACH

Research historical documentation on the compressed air system

Analyze potential area of improvements

Submit an Engineering Change Request (ECR)

Design experiments and test the system during Major Scram

Recommend improvements and contact manufacturer for proper 

replacements

Cost analysis of labor and replacement parts

Modify drawing E-60-017 (if needed)
PURPOSE

 To test the reliability of the compressed air 

system given the aging equipment and plant 

modifications.

 A compressed air system study is required 

to determine how the system is functioning 

and what modifications, if needed, are 

required to return the system to design 

specifications.

 Identification of changes that are required 

for the system to be up to industry standard.

 System Documentation.

EXAMPLE

June 12th - The 

confinement back door was 

found deflated.

Possible causes:

• Regulator

• Solenoid valve

• Clogged airline 

Concluded: 

The door will inflate but 

very slowly. Not allowed to 

use the door unless there is 

an emergency.
PRESSURE DROP

 Allow measurement of the change in pressure in undesirable locations, identify leaks, 

and observe any changes that affect the system.

 Is the change in pressure significant?

 Experiment setup

 Prior to Major Scram isolate PAV12, CAV 21 and install transducers, close 

valve CAV 103 and 104 then relieve the pressure in the air dryer, install the 

transducers in place on the air dryer relief then isolate CAV 93 and install the 

transducer in CAV 93A. Apply snoop to check for air leaks when installing and 

resetting the equipment.

 Program monitors. 
MATERIALS

 Pressure gauge: Identify the pressure in the regulator.

 Wire: To carry the electrical signal converted from the transducer to the recorders.

 Yokogawa monitors: Used to record the signal, time of the operation, and chart the data received from the transducers.

 8v-30v Power Source: Supply power to the transducers.

 Snoop: Leak detector for connections.

 Pressure transducers: Seven transducers will be used to change difference in pressure across the system into an electrical 

signal.

2 core 22awg wire, 500’ DX1006N

EXPECTED RESULTS

 Expected to see some loss but not significant amount to affect the system due to 

leakage or pressure drop in undesirable location.

 Possible reasons for pressure drop:

a) Incorrectly connected pressure transducer

b) Clogged filters and pipes

c) Not enough pressure in the receivers

d) Regulator malfunction

e) Leaks in pipes
RESULTS

65.48

69.93

69.63

66.48

70.04

64.00

65.00

66.00

67.00

68.00

69.00

70.00

71.00

0 100 200 300 400 500 600 700

Pressure (Psig)

Data/ 2s

PAV 12

68.75

65.68

73.36

69.17

65.70

72.90

64.00

65.00

66.00

67.00

68.00

69.00

70.00

71.00

72.00

73.00

74.00

0 100 200 300 400 500 600 700

Pressure (Psig)

Data /2s

CAV 21
98.91

96.01

97.09

96.47

96.20

98.52

95.50

96.00

96.50

97.00

97.50

98.00

98.50

99.00

99.50

0 50 100 150 200 250 300 350

PRESSURE (PSIG)

DATA POINT/ 2S

AIR DRYER
ENGINEERING CHANGE REQUEST (ECR)

The purpose is to remove and replace old, discontinued, obsolete, broken, and 

faulty valves and replace them with modern components.

 Estimated cost of replacement solenoid valves: $37,575.00

 Engineering Effort: 440 hours

 Operating Effort: 600 hours
CONCLUSIONS

 Reproducible Test

 No air leakage

 Negligible amount of pressure drop

 Achieved confinement in 12s

 Valve activation in 1.5s

 Replace critical components for preventative maintenance 
FUTURE TESTS

 1. Pressure relief with compressor- To observe the speed and efficiency of the compressor by 

recording the time used to fill the receivers with the compressor.

 2. Pressure relief with receivers- Observe valves response to the difference in air for pressure drop 

and observe the amount of air used by the valve and how long until an issue arises. 

 Speed requirement test- Since there is no specified time requirement for the solenoid valve closure 

(generally assumed to close in 5 seconds) (optional).

 3. Minimum air required for use in single cycle- Enabling us to see how well/ how long the system 

works and the status of the confinement with just half the pressure in the receivers.

 4. Pressure drop test -Allowing measurement of the change in pressure in undesirable locations, 

identify leaks, and observe any changes that effect the system.
ACKNOWLEDGEMENTS 

 Thanks to the Reactor Operations and Engineering group

 Special thanks to:

 Julie Borchers

 Joe Dura

 Dan Hughes, Chief of Reactor Operations

 Paul Brand, Chief of Reactor Engineering

 Oscar Wiygul

 Scott Arneson

 Sam McDavid

 Ricky Sprow

 Dan Mattes
MENTOR- MARCUS SCHWADERER
DISCLAIMER

Certain commercial equipment, instruments, or materials are identified in this 

presentation to foster understanding. Such identification does not imply recommendation 

or endorsement by the National Institute of Standards and Technology, nor does it imply 

that the materials or equipment identified are necessarily the best available for the 

purpose.