Ludlum Measurements 43-37 User manual

MODEL 43-37 AND MODEL 43-37-1
GAS PROPORTIONAL DETECTORS
December 2016
Serial No. 086152 and Succeeding
Serial Numbers

MODEL 43-37 AND MODEL 43-37-1
GAS PROPORTIONAL DETECTORS
December 2016
Serial No. 086152 and Succeeding
Serial Numbers

WARRANTY CERTIFICATE
Ludlum Measurements, Inc. warrants the products covered in this instruction manual to be
free of defects due to workmanship, materials, 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 those intended.
There are no warranties, expressed or implied, including without limitation any implied
warranty of merchantability or fitness, which extend beyond the description of the face
thereof. 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 the
product.
RECEIVING CONDITION EXAMINATION
Be sure to verify that the shipping carton is received in good condition with no visible
damage. Should the instrument be received in a damaged condition, save the shipping container
and the packing material and request an immediate inspection by the carrier.
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
915-235-5494
FAX [phone]

Model 43-37, 43-37-1 Gas Proportional Detectors
December 2016
page i
TABLE OF CONTENTS
1. GENERAL...................................................................................................................................1
2. SPECIFICATIONS......................................................................................................................1
3. PRELIMINARY INSTRUCTIONS.............................................................................................2
4. HOOK-UP....................................................................................................................................2
5. FLUSH.........................................................................................................................................2
6. DETECTOR PERFORMANCE..................................................................................................3
7. STATIC OPERATION................................................................................................................3
8. RECHARGE................................................................................................................................4
9. PARTS LIST................................................................................................................................4
DRAWINGS & DIAGRAMS....................................................................................................5

Model 43-37, 43-37-1 Gas Proportional Detectors
December 2016
page ii

Model 43-37, 43-37-1 Gas Proportional Detectors
December 2016
page 1
1. GENERAL
The Ludlum Model 43-37 and Model 43-37-
1 are large-area gas proportional detectors,
designed to be used with the Ludlum Model
239-1 Floor Monitor. They are designed for
alpha and beta survey and are compatible
with a number of counting instruments.
Although similar in many performance
specifications, the Model 43-37-1 is 7 inches
longer than the Model 43-37. (Refer to
assembly drawings at the end of this
manual.) Instructions and procedures for the
Model 43-37 also apply to the Model
43-37-1, except where noted.
2. SPECIFICATIONS
WINDOW THICKNESS:
Alpha only: 0.8 mg/cm2(2 layers of
aluminized mylar)
Beta-gamma: 3.4 mg/cm2(1 layer of
aluminized mylar and 1 layer of clear mylar)
Gamma: 11.8 mg/cm2(1 layer of aluminized
mylar and 1 layer of drafting mylar)
WINDOW AREA:
Model 43-37: 584 cm2active
434 cm2 open
Model 43-37-1: 821 cm2active
609 cm2 open

COUNTING GAS: P-10 (10% methane, 90%
argon) is recommended. Other counting gasses
are also acceptable.

GAS RECHARGE: Expected time of
operation on static charge with 39-inch cable:
Gross counting mode - 15 hours or longer
Alpha-beta mode - 5 hours or longer
OPERATING VOLTAGE:
Alpha - Typically 1100 - 1400 volts
Beta-Gamma -Typically 1700 - 1800 volts
COUNTER THRESHOLD SETTING:
Typically 4 mV for scaler or gross counting
instrument
BACKGROUND:
Alpha - less than 10 counts per minute
(cpm), when operating at alpha-only
plateau region
Beta-Gamma - Model 43-37: Typically
800-1300 cpm (in 10R/hr field)
Model 43-37-1: Typically 1000 -
1800 cpm (in 10R/hr field)
EFFICIENCY (4 pi geometry): Typical
values for gross counting -
20% 239Pu (alpha only);
30% 99Tc (beta only)
30% 90Sr/90Y
less than 1% gamma
or for alpha-beta counting -
17.5% 239Pu
20% 99Tc
20% 90Sr/90Y
less than 1% gamma
SIZE: Model 43-37:
2.5 x 15.9 x 46.4 cm (1 x 6.25 x 18.25 in.)
(H x W x L) (not including fittings)
Model 43-37-1:
2.5 x 15.9 x 64.1 cm (1 x 6.25 x 25.25 in.)
(H x W x L) (not including fittings)
WEIGHT:
Model 43-37: 1.9 kg (4.1 lb)
Model 43-37-1: 2.4 kg (5.4 lb)
GAS CONNECTORS: Double-end quick
disconnects
SIGNAL CONNECTORS: Series “C,”
unless specified

Model 43-37, 43-37-1 Gas Proportional Detectors
December 2016
page 2
3. PRELIMINATRY INSTRUCTIONS.
UNPACKING AND REACKING
Remove the calibration certificate or
detector functional check certificate and
place it in a secure location. Remove the
detector and accessories (cable, etc.) and
ensure that all of the items listed on the
packing list are in the carton. If more than
one detector is in the carton, refer to the
calibration certificiate(s) for serial number
match. The Model 43-37 and 43-37-1 seral
number is located on the side of the detector
near the connector.
To return the instrument for repair or
calibration, provide sufficient packing
amterial to prevent damage during shipment
and appropriate warning labels to ensure
careful handling.
Every returned instrument must be
accompanied by an Instrument Return
Form, which can boe downloaded from the
Ludlum website at www.ludlums.com. Find
the for by clicking the “Support” tab and
selecting “Repair and Calibration” from the
drop-down menu. Then choose the
appropriate Repair and Calibration division
where you will find a link to the form.
4. HOOK-UP.
NOTE: Plastic dust caps should always be
in place on detector gas connectors when gas
lines are disconnected, except during a fast
flush. Dust caps prevent dust and other
materials from interfering with the function
of the check valves and should be in place
when the detector is operating on a static
charge.
Proper hook-up procedure requires
connecting the counting gas and input lines
together.
RECOMMENDED EQUIPMENT:
DUAL-STAGE REGULATOR:
One stage to show supply pressure;
second stage to reduce supply
pressure to 1-2 psi.
NEEDLE VALVE between second
regulator stage and flowmeter for
easier flow adjustment.
FLOW METERS: Range of 0-100
cubic centimeters/minute (cc/min).
5. FLUSH
CAUTION: The Models 43-37 and 43-37-1
use double-ended quick connects. Both the
male and female quick connects have to be
connected to allow counting gas to flow
through the detector.
Connect output gas line from
detector to output flowmeter.
Connect input and gas lines from
main supply through the regulator
and input flow meter.
Turn main supply on and flush
detector as follows:
Model 43-37 –100 cc/min for 30
minutes

Model 43-37, 43-37-1 Gas Proportional Detectors
December 2016
page 3
Model 43-37-1 –100 cc/min for 45
minutes
A faster flush time can be achieved by
increasing the flow rate. (In general, if the
flow rate is doubled, the flush time can be
cut in half.)
CAUTION:
The main supply should be reduced to less
than 50 cc/min before the output gas line is
reconnected.
After flush is complete, set flow to
30-50 cc/min.
Check output flowmeter. Determine
detector leakage to be less than 5
cc/min.
6. DETECTOR PERFORMANCE
ALPHA PLATEAU: Determine the
plateau region of the background and alpha
source counting curves for the applied
voltage range of 1100-1400 volts. Use 50-
volt increments and set the counting
instrument input sensitivity at 4 mV. The
operating voltage should be approximately
1250 volts. The background count should
be 10 cpm or less. The operating voltage
will increase with a higher input sensitivity.
Check each section of the detector face for
statistically uniform response, that is, ensure
that each section reading is within 10% of
the average of the readings. If the count is
not statistically uniform, check for light
leaks in the window and repeat flush
procedures.

BETA-GAMMA PLATEAU: Determine
the plateau region in the background and
beta-gamma source counting curves for the
applied voltage range of 1500 volts to 1900
volts or from 1500 volts to when either the
source or background count rate increases
dramatically. Use 50-volt increments and
leave the input sensitivity at 4 mV. The
operating voltage should be approximately
1700-1800 volts, with the background count
as stated in Section 2 Specifications. Setting
instrument input sensitivity greater than 4
mV will increase the operating voltage.
7. STATIC OPERATION.
Check detector for proper operation, for
appropriate source count, and gas
leakage.
Disconnect output and input male quick
connects.
Turn main supply to OFF.
Check source count before and after
static operation. A decrease in detector
efficiency should be less than 10% in 15
hours from when the detector is
disconnected from main gas supply.
NOTE: There is expected performance
degradation along the sides of the probe and
within an inch of the standoffs.

Model 43-37, 43-37-1 Gas Proportional Detectors
December 2016
page 4
8. RECHARGE
Connect output and input quick
connects.
Turn main supply to ON at 30-50 cc/min
for routine recharge, or refer to flush
procedures for faster flush time.
9. PARTS LIST
Ref. No.
Description
Part No.
Completely Assembled
Model 43-37 Gas Probe
47-1143
Completely Assembled
Model 43-37-1 Gas Probe
47-2243
Body –Model 43-37
7304-007
Body –Model 43-3-1
7304-036
1 EA.
Detector Cover (Face) Model 43-37
7304-010
1 EA.
Detector Cover (Face) Model 43-37-1
7304-028
1 EA.
Hex Screen –Model 43-37
7304-011
1 EA.
Hex Screen –Model 43-37-1
7304-025
1 EA.
Holding Ring –Model 43-37
7304-012
1 EA.
Holding Ring –Model 43-37-1
7304-030
1 EA.
Series "C" Connector
13-7751
2 EA.
Quick Disconnect Fitting Stem
13-7912
2 EA.
Quick Disconnect Fitting Pipe
13-7920
10 EA.
Standoff
18-8807
9.26 FT.
Silicone Cord - Model 43-37
22-9631
12 FT
Silicone Cord - Model 43-37-1
22-9631
2 EA
Dust Cap
22-9785

Model 43-37, 43-37-1 Gas Proportional Detectors
December 2016
page 5
DRAWINGS & DIAGRAMS
Assembly View (Model 43-37), Drawing 304 x 18
Assembly View (Model 43-37-1), Drawing 304 x 41