Ludlum Measurements 239-1F User manual

LUDLUM MODEL 239-1F
FLOOR MONITOR
Revised December 2010
LUDLUM MEASUREMENTS, INC.
501 OAK ST., P.O. BOX 810
SWEETWATER, TX 79556
325/235-5494 FAX: [phone]

STATEMENT OF WARRANTY
Ludlum Measurements, Inc. warrants the products covered in this manual to be free of
defects due to workmanship, material, and design for a period of twelve months from the
date of delivery. The calibration of a product is warranted to be within its specified
accuracy limits at the time of shipment. In the event of instrument failure, notify Ludlum
Measurements to determine if repair, recalibration, or replacement is required.
This warranty excludes the replacement of photomultiplier tubes, G-M and proportional
tubes, and scintillation crystals which are broken due to excessive physical abuse or used
for purposes other than intended.
There are no warranties, express or implied, including without limitation any implied
warranty of merchantability or fitness, which extend beyond the description of the face
there of. If the product does not perform as warranted herein, purchaser’s sole remedy
shall be repair or replacement, at the option of Ludlum Measurements. In no event will
Ludlum Measurements be liable for damages, lost revenue, lost wages, or any other
incidental or consequential damages, arising from the purchase, use, or inability to use
product.
RETURN OF GOODS TO MANUFACTURER
If equipment needs to be returned to Ludlum Measurements, Inc. for repair or calibration, please send to
the address below. All shipments should include documentation containing return shipping address,
customer name, telephone number, description of service requested, and all other necessary information.
Your cooperation will expedite the return of your equipment.
LUDLUM MEASUREMENTS, INC.
ATTN: REPAIR DEPARTMENT
501 OAK STREET
SWEETWATER, TX 79556
800-622-0828 325-235-5494
FAX [phone]

Model 239-1F Floor Monitor
December 2010
TABLE OF CONTENTS
1. GENERAL............................................................................................................................... 1
2. SPECIFICATIONS ................................................................................................................. 1
3. GAS BOTTLE INSTALLATION.......................................................................................... 2
4. OPERATING PROCEDURES .............................................................................................. 2
5. MAINTENANCE.................................................................................................................... 3
6. REPLACEMENT PARTS LIST ............................................................................................ 4

Model 239-1F Floor Monitor
December 2010
Model 239-1F Floor Monitor shown with
Ludlum Model 2221

Model 239-1F Floor Monitor
December 2010
1. GENERAL
The Model 239-1F Floor Monitor is a gas
proportional floor monitor detector mounted on
a roll-around cart. The instrument features a
flow system, quick-connects, a gas bottle
mount, and a means to adjust the height of the
detector from the floor for optimum
performance. A nuclear counting gas bottle,
gas regulator, and a survey instrument are
required for the operation of the floor monitor.
The survey instrument should be capable
of supplying up to 2500 volts to the detector.
The floor monitor utilizes quick-connect
fittings on the supply side of the input flow
meter and the external outlet line of the output
flow meter for flow operation. An input line to
the flow meter with quick-connect is attached
from the portable gas bottle mounted on the
frame of the cart.
2. SPECIFICATIONS
•DETECTOR SIZE: 2 x 16 x 46.5
cm (0.8 x 6.3 x 18.3 inch) (H x W x L)
•DETECTOR ACTIVE AREA: 584
cm2
•ADJUSTABLE HEIGHT: Detector
adjusts from 0 inches to 1½ inches from floor
•WINDOW MATERIAL: (a) 0.4 or
0.8 mg/cm2(one or two layers metalized
mylar) alpha, beta/gamma; (b) 3.9 mg/cm2
(one layer metalized mylar, one layer 3.5
mg/cm2mylar) beta/gamma; (c) 7.9 mg/cm2
(one layer metalized mylar, one layer 7.5
mg/cm2mylar) gamma
•EFFICIENCY (4π): 17%-239Pu;
25%-90Sr/90Y; gamma <1%. Efficiencies are
expressed in 4pi geometry and calculated with
a probe using the 0.8 mg/cm2 Mylar window
at a fixed height of 3/16 inches distance from
the floor
•COUNTER: Any instrument suitable
for use with proportional detectors and
capable of 2500V operation.
•CONNECTOR: Series "C" type
•QUICK-CONNECTS: Swagelock
(brand) 1/8 mpt to 1/4 O. D. tubing.
•GAS CONSUMPTION:
approximately 35 cc/min.
•FLOW METERS: Both IN and OUT
0-100 cc/min.
•FLOW RATE: 35 cc/min after
purging
•MAXIMUM GAS CYLINDER
SIZE: Size is 9 inch diameter x 26 inches;
0.60 cu. ft. capacity
•WIRE: 0.001 inches diameter
platinum (8 % Tungsten alloy)
•STANDOFFS: Concord 1102-23 -
0019
●CART:
∗Handle Height: 3.5 ft.
∗Length: 66.04cm (26 inch),
including wheels, but excluding
handle.
∗Width: 46.36 cm (18.25 inch)
∗Wheel Size: Rear 8 inches, front 3
inches swivel.
∗Finish: Computer Beige powder
coat paint.
•WEIGHT: 20 lbs. without gas cylinder
and counting instrument.
3 See instrument manual for specifications and instructions for the counting instrument.
page 1

Model 239-1F Floor Monitor
December 2010
3. GAS BOTTLE INSTALLATION
1. The instrument typically comes with a regulator, a valve, a brass fitting, two white plastic
compression nuts, and some vinyl tubing. The valve is in the box with the regulator, the
other parts may be in a separate bag.
2. Screw the valve into the output of the regulator. If there is an arrow on the valve, it should
point away from the regulator. Screw the fitting onto the valve. Use Teflon tape or sealant
on the connections.
3. Set the gas bottle onto the cart and secure with the provided strap. To adjust the strap, open
the buckle completely, extend or retract the strap through the latch as necessary then close
the buckle. Attach the regulator onto the bottle.
4. Remove the existing nut from the fitting on the regulator. Insert one end of the vinyl tubing
into one of the plastic nuts and screw the nut onto the fitting. Finger tight is sufficient.
5. Cut the subbing to the desired length to reach the top of the box on the handle of the cart that
has the flowmeters. Remove the existing nut from the fitting on the quick disconnect above
the “IN” flowmeter. Insert the other end of the vinyl tubing into one of the plastic nuts and
screw the nut onto the fitting. Finger tight is sufficient.
6. Proceed to the operating procedures section of this manual.
4. OPERATING PROCEDURES
3CAUTION: If the output has a quick-
connect fitting, insert a male quick-connect
prior to applying the gas supply.
oTurn the flow control valve off.
3CAUTION: Do not overtighten.
oTurn valve on gas supply bottle to the
OPEN position. The high pressure regulator
should show the supply pressure from the gas
bottle.
oTurn outlet regulator valve clockwise to
register between 3-5 psi.
oOpen the flowmeter valve on the cart's
input flowmeter. Adjust the input flowmeter to
100 cc/min to flush the air out of the detector.
After flush, flow may be reduced to 35 cc/min.
Allow 10 minutes to purge the system.
3 NOTE: The outlet flow indicator on
the flowmeter box will not immediately
indicate flow when system is first turned
ON. The primary purpose of the outlet
flowmeter on the flowmeter box is to check
for system leaks. This process is addressed
in the Maintenance Section to follow.
oConnect the detector to the counting
instrument
(1) HV is preset at the factory to read
alpha, beta, and gamma.
(2) Background count will read
approximately 1000-1400 cpm.
(3) If only alpha detection is required,
the HV may be adjusted to where the
background will read 0-5 cpm.
oAdjust the height of the detector for
optimum performance.
page 2

Model 239-1F Floor Monitor
December 2010
5. MAINTENANCE
Periodic maintenance consists of checking
the general condition of the detector, gas
tubing/fittings, signal/HV cable, and the
window. Malfunction of the detector could
be caused by a gas leak or a broken HV wire
inside the detector.
In case of low count, the detector should
be checked for gas leaks. Check the input and
output flowmeter on the cart. A reduced or
no output flow compared to the input would
indicate a gas leak in the system. Any holes
in the window will allow counting gas to
escape causing degradation of detector
efficiency. If the window needs replacing in
the detector, the detector should be checked
both for gas leaks and HV shorts before
replacing detector on the cart.
Indication of a broken wire is low or
erratic HV reading. Foreign particles, wire
tails on the standoff posts, or solder peaks can
cause excessive counts. Loose wires can
cause reduced count.
To replace a broken or loose wire, remove
the window, being careful not to tear or
puncture the window material. Replace the
wire and clean the chamber thoroughly.
Inspect the gasket for proper condition before
replacing the window. Check for gas leaks
and proper operation before installing the
detector on the cart.
page 3

Model 239-1F Floor Monitor
December 2010
6. REPLACEMENT PARTS LIST
QTY. DESCRIPTION PART NO.
MODEL 239-1F FLOOR MONITOR CART 48-1427
1 EA 2 Stage-Regulator 8L-350 310017
1 EA Tie Down Assembly 2310124
1 EA M 239-1F Welded Cart Assy. 4404-027
2 EA Shoulder Bushing 7175-010-01
2 EA Brass Washer 7175-010-02
2 EA Hand Knob 7175-010-03
2 EA Stud 7175-010-04
1 EA Manifold Blocks 7175-014-01
1 EA Box Side 7175-014-03
1 EA Box Back 7175-015-01
2 EA Probe Holder Bracket 7304-013
2 EA Side Bracket 7404-021
1 EA Main Box Screened 9175-014
1 EA 5 Ft. "C" Cable 8303-022
10 EA PLT2M Cable Tie 03-5410
4 EA Stem Fit-B-OC4-D-400 13-7912
2 EA M Pipe Fit-B-QC4-B-2PM 13-7920
2 EA Grommet-2170 18-8774
1 EA Flowmeter-RMA-150-SSV 21-9547
1 EA Flowmeter-RMA-150 21-9548
15 FT. Vinyl Tubing 59002 22-9514
12 FT. Swaglok-B-400-1-2 22-9522
10 EA Swaglok-Insert B-405-2 22-9639
28 IN. Edge Trim 8451A53 22-9828
REGULATOR 2310017
SMALL CAN ASSEMBLY 4175-096
LARGE CAN ASSEMBLY 4175-062
MODEL 43-37 GAS PROPROTIONAL DETECTOR 47-1143
1 EA Face Assembly 4304-017
1 EA Hex Screen 7304-011
1 EA Holding Ring 7304-012
1 EA Screw-In "C" Connector 4478-011
2 EA Pipe Fitting 13-7920
10 EA Standoff 18-8807
9.3 FT Silicone Cord 22-9631
Page 4