Palmer Lmic Manual

Palmer Environmental
Ty Coch House
Llantarnam Park Way
Cwmbran
NP44 3AW
United Kingdom
Tel: [phone]
Fax: [phone]
Email: [email protected]
Web: www.palmer.co.uk
Lmic Operators Guide Issue 1
September 2002
Lmic
Operators Guide
Contents Page
Introduction 1
Controls 1
Using the Lmic 2
Care of the Lmic 2
Battery warning 2
Battery replacement 2
Charging the Lmic batteries 2
Operator Guidance 3
Technical Specification 4
Warranty 4

Lmic
The Lmic (pronounced “el mike“) is an easy-to-use,
low cost, electronic listening stick and ground micro-
phone combined. It is ideal for general leak sound-
ing operations and can be fitted with either a tripod
foot (for use as a ground microphone) or probe rods
(for sounding at fittings or in soft ground).
The control unit is hand-held with a “trigger” opera-
tion and a volume/sensitivity rotary control. An LED
indicates operation and battery status. It can be
used to confirm the position of underground leaks
audibly from ground level; sound pipe fittings;
penetrate soft ground to listen for leaks or carry out
traditional acoustic surveys.
Equipment list
1 Lmic hand held control unit
2 Microphone unit with cable
3 Tripod unit
4 2 probe rods
5 AC adapter
6 Headphones
7 Carry bag
8 Instruction manual
Lmic Controls
Headphones /
battery charger
connection
Trigger
switch
Micro-
phone
connection
The Lmic equipment
LED Rotary volume/sensitivity
control
1
3
6
4
2
7
The Lmic equipment is shown above (note the
battery charger and manual are not shown).
Top view of the Lmic showing the rotary control for
volume and sensitivity.
Bottom view of the Lmic showing the trigger switch
and the electrical connections for the headphones/
battery charger and microphone.
1

Using the Lmic
The Lmic is simple to operate. Select either the probe
rods or the tripod unit and screw into the microphone
unit. (Use the tripod foot on hard ground and use the
probe rods on soft ground or when accessing water
pipe fittings). Connect the headphones to the rear
connector and connect the microphone cable to the
forward connector. Put on the headphones and press
the trigger button underneath the hand-held unit to
listen for leaks. The volume/sensitivity can be
adjusted using the rotary control.
LED indication
The green LED shows when the unit is operating and
the red LED indicates low battery power.
Care of the Lmic
The Lmic is rugged and showerproof (to IP65) but
contains electronic circuitry and should be handled
with care. It should be kept clean and dry and where
necessary cleaned with a damp cloth; abrasive
materials must not be used.
Battery Warning
The Lmic contains lithium ion batteries which must not be used under any circumstances on any other equip-
ment if removed. Only batteries supplied by Palmer Environmental must be used as replacements. Do not short
circuit or misuse these batteries as this may result in explosion or fire.
Battery replacement
Although these batteries are rechargeable they may eventually need to be replaced. To do this undo the two
screws underneath the hand-held unit and separate the two halves of the Lmic unit. Gently pull out the battery
holder and replace the batteries. When refitting the batteries and battery holder make sure no wires become
trapped.
Charging the Lmic batteries
Connect the charger lead to the rear connector of the Lmic and connect the charger power lead to the 240V AC
supply. The Lmic can then be charged overnight. An optional accessory is the car cigarette lighter adapter that
can also be used to charge the batteries.
The Lmic in use
The Lmic connected to the universal 110-240V AC charger
2

Lmic Operator Guidance: Background
information to effective acoustic leak detection
All acoustic leak detection methods are based on the
premise that normal water passage through pipelines
takes place noiselessly. When the water passage is
disturbed a noise is created. Causes can include par-
tial pipe blockages, sudden changes in pipe diameter,
abrupt changes in pipe direction, pumps or meters in-
stalled in the pipeline, consumer usage or pipeline
damage. Pipeline damage can include holes, cracks or
splits, complete pipeline rupture, leaking joints or leak-
ing valves.
Careful application of leak detection techniques will
enable the operator to eliminate detected noises gen-
erated by poor pipeline design or consumer usage and
to identify leakage due to pipe system damage.
The strength and clarity of noise generated by leaks
will be affected by the water pressure, the size and
shape of the orifice allowing leakage, the type of
ground material around the pipeline, the type of
ground cover over the pipe, the diameter, wall thick-
ness and material of the pipeline and the quantity of
water leaking.
A small orifice or hole and high water pressure gener-
ally produce a higher frequency noise. Often the noise
level increases around valves, pipe elbows, T connec-
tions, pipe ends, etc. since the partial obstruction in-
creases pressure and creates some further distur-
bance in the water path.
Leak noise is transmitted along the pipeline both
through the water and the pipe wall as well as into the
ground around the pipe. The noise travels much better
through "hard" materials so that the noise travels
much further along metallic pipes than asbestos ce-
ment pipes which themselves are better than plastic
pipes. Ground material generally provides a poorer
travel path than the pipeline itself. Soft sandy ground
provides a worse travel path than well compacted
ground with a hard paved surface covering.
The leak noise can change in strength and pitch as it
travels along the pipe or through the ground. The
deeper the pipe is buried and the softer the ground the
more the noise will be dampened. The harder the pipe
material, the higher the frequencies detected will be,
and the further from the leak the noise will be detected
and the harder it becomes to accurately pinpoint the
exact point of maximum.
Background noise can interfere with leak detection.
Traffic and machinery noises can travel for consider-
able distances through both air and ground material
and often occur in the same frequency bands as leak
noise. Sometimes it is necessary to use leak detec-
tion techniques at night when interfering noises are
less.
It is very important to adopt a methodical approach
when using any instrument for acoustic leak detection.
It is necessary to practice the technique in order to dis-
tinguish between different sounds, recognising back-
ground or interfering noises, so that they can be elimi-
nated. It is also essential that other (non-leakage)
noise sources such as consumer draw-off or partially
closed valves are eliminated by logical site inspection
practices prior to any excavation taking place.
Hand probe
For normal soft ground surfaces the single pointed ex-
tension rod should be connected - do not overtighten
the screw thread. For direct contact with underground
fittings via access covers it may be necessary to use
the second extension rod - remove the single rod and
connect the extension rod - replacing the pointed rod
again. If the rods have been overtightened, spanner
slots allow easy removal.
Surveying
The leak location can be narrowed down by listening
at accessible contact points such as meters, hydrants,
valves and stop-taps, which provide points of good
sound pick-up particularly if the pipe is metallic. Use
the hand-probe/extension rod to listen at these points.
If there are no accessible contact points or if the pipe
is of non-metallic material use the microphone foot for
listening, placing the foot over the pipe route in the
area of the suspected leak. Move along the pipe route
listening at each accessible pipe-fitting or at regular
positions on the ground until you have identified the
area of maximum noise level.
Note: When you are listening on pipe-fittings the loca-
tion of the point of maximum noise will probably not
indicate the leak position, only the fitting closest to the
leak. The noise level will also appear stronger where
there is less thickness of ground or other material for it
to pass through. The leak noise will follow the path of
least resistance.
Pinpointing the leak position
Pinpointing the leak position involves a process of
comparing a number of leak noises. Select the most
suitable sensor device; the microphone foot for hard
ground surfaces or the hand probe for soft ground.
Press the trigger to operate the Lmic and adjust the
headphone volume control to a comfortable listening
level. Once you have listened to the noise through the
headphones, release the trigger to switch off the am-
plifier and move the microphone foot or hand probe to
the next test position.
Repeat the sequence to listen to each of the test loca-
tions moving along the pipe route in the direction
where signal strength is increasing. If the leak noise
level falls you have passed the leak and should go
back and reduce the distance that you move between
measurements. The loudest leak noise will then indi-
cate the location of the leak bearing in mind the
ground conditions already mentioned.
3

Technical specification
Lmic hand held unit/sensor housing
Piezoelectric high sensitivity sensor mounted in PC-ABS (polycarbonate) housing
Single headphone/charger input socket with automatic sensing of device connected
Connectors
Amphenol military specification connectors for microphone and headphone/charger connections
Charging
Universal 110-240V AC charger with 12V DC output
Car cigarette lighter adapter with 12V DC output (optional accessory)
4-pin Amphenol connectors to control unit
Charge time: Overnight charge.
Microphone housing
High sensitivity piezo-electric sensor mounted in rubber housing with integral strain relief
Low noise 0.75m cable (detachable)
4-pin Amphenol connection to control unit
Weight: 400g
Foot attachment
Cast metal tripod for ground contact
Hand probe attachment
2 stainless steel extension rods (each 400mm long)
Weight: 150g
Headphones
Lightweight high quality headphones
Impedance: 16 Ohms
4-pin Amphenol connector to control unit
LED
Green = normal operation
Red = low battery power
Optional accessories
•High specification aviation quality headphones
•Car cigarette lighter adapter with 12V DC output
•Acoustically shielded ground microphone foot, for use in all weather conditions
Warranty
All equipment is warrantied by Palmer Environmental Ltd to be free from defects in materials and workmanship for
a period of one year (unless otherwise stated) from the date of shipment to the original customer. This warranty is
only valid if the equipment has been installed and used in the correct manner as described in this manual.
Repair or replacement (at Palmer Environmental’s option) will be made without charge provided the above
conditions have been met.
If any problems occur, notify Palmer Environmental Ltd or its authorised representative giving full details of the
problem, and the model and serial number of the equipment. You will receive technical advice and/or shipping
instructions depending upon the nature of the problem.
Palmer Environmental Ltd Tel: [phone]
Ty Coch House Fax: [phone]
Llantarnam Park Way email:[email protected]
Cwmbran http://www.palmer.co.uk
NP44 3AW
4