Milltronics ST-50 Instruction Manual

ST-50 SERIES

ULTRASONIC TRANSDUCER

Instruction Manual

PL-418

December 1994

33454180
Rev 1.2

T

hank you for purchasing Milltronics products. We endeavour to design
equipment that is simple to use and reliable in its operation, with the aim of satisfying
our customers needs.

Mill tronics has been designing and manufacturing process equipment since 1954.
Our fields of expertise include ultrasonic level measurement, in-line weighing of dry
bulk solids and motion sensing.

Milltronics is established world wide through associate offices and representatives.
Our network is continua lly b eing re fined to provide our customers with first rate
sales information, engineering assistance and after sales support.

For more details on our products and service, please contact us and we will provide
you with a listing of the offices or representatives nearest you.

P.O. Box 4225
730 The Kingsway
Peterborough, ON
Canada K9J 7B1

Tel. [phone]
Fax [phone]

709 Stadium Drive
Arlington, Texas
U.S.A. 76011

Tel. [phone]
Fax [phone]

Oak House
Everoak Estate
Bromyard Road
Worcester, WR2-5HP
England

Tel. [phone]
Fax [phone]

Château de la Saurine
Pont de Bayeux
B.P. 6
13590 Meyreuil
Aix en Provence
France

Tel. [phone]
Fax [phone]

ABOUT THE TRANSDUCER

The ST-50 series of transducers operates in association
with Milltronics ultrasonic level monitoring products.

transducer

The transducer converts the electrical energy of the
transmit pulse from the transceiver into acoustical energy.
It then converts the acoust ical energy of the echo back
into electrical energy for the transceiver receive period.

The effective acoustical energy is generated from the
transducer face and is radiated outward, decreasing in
amplitude at a rate inver sely proportional to the square
of the distance. Maximum power is radiat ed axial ly
(perpendicular) fr om the t ransducer face in a line referred
to as the axis of transmission. Where power is reduced by
half (– 3 dB), a conical boundary defining the sound beam,
centered about t he axis of transmission is est ablished. The
diametric measurement of the cone in degrees defines the
beam angle. Impedance m atching techniques are used to
optimize the transfer of power from the transducer into air
and from the air back into the transducer.

face

transducer

boundary

bea m

angle

axis of
transmission,
perpendicular
to transducer
face

SPECIFICATIONS

Model : » ST-50
Measurement r an ge : » typically 0.3 m - 15 m (1-50 ft) restricted to tra nsce iver maximum

Temperature range : » – 40 to 93 °C (– 40 to 200 °F)
Frequency : » typically 44 KHz, transceiver dependent
Beam angle : » 5°

*

: » 3.9 Kg (8.5 lb)

Weight
Construction : » CPVC housing with polyurethane face

» 1" NPT mounting/conduit connection with neoprene jacketed cable
» tot a lly encapsulated
» options: » f langing: the transducer can be fact ory flanged,

» facing: » CPVC for corrosive applications

Separation : » typical ly 365 m (1200 ft) from associated transceiver
Approvals : » CSA, FM and BASEEFA / CENELEC

*

approximate shipping weight of transducer with standard cable length and unflanged

▲

refer to associated transceiver manual

✧

the maximum temperature for polyethylene foam facing is 77 °C (170 °F)



is a registered trade mark of Dupont

Teflon

✧

consult Mi lltronics



» Teflon

for corrosive appl ications

» polyethylene foam for dry-dust applications

▲

– 3 db

5°

▲

PL-418 1

95/07/11

OUTLI NE AND CONNECTION

*Cable length: » standard: 5 m ( 16 ft)

» optional: consult Milltronics

*,

cable
PVC jacket

black

white

junction box

hot

Milltronics
transceiver

S
H

I

H

E

O

L

T

D

1" NPT

shield

RG62 A/U
coaxial cable

OR

black

white

125 mm

140 mm

(5.5") dia.

(4.9")

CPVC housing

radiating surface
(see Specification \ Construction)

direct connection

DO’ S AND DON’TS

VERY IMPORTANT

Do not route cable openly in raceways.
For optimum isolation against electr ical noise, run cable in a grounded metal conduit with no

other cabling (except temperature sensor). Ground shield only at transceiver. Insulate shield
at junctions to prevent inadvertent grounding.

shield

Transducer wir ing must be done in conjunction with approved conduit, boxes and fittings
and to procedures in accor dance with all governing regulations.

Seal a ll thread connections to prevent ingress of moist ure.
Do not run cable near high voltage or current runs, contactors and SCR control drives.
For BASEEFA Zone 0, cable must be terminated externally to Zone 0 in an appropriate

manner. The cable must be protected against mechanical damage, and arrangements sealed
to prevent migration of atmosphere from zone 0.

To reduce risk of elecrost atic discharge, housing (except free) must be covered with copper
mesh and grounded.

PL-418 2

96/03/19

MOUNTING

DO’S AND DON’TS

VERY IMPORTANT

Mount the tr ansducer so that it is

. Refer to the associated transceiver manual.

value
Do not mount the transducer directly to metal
Do not overtighten mounting

liquid applications

On

, the t ransducer mus t be mounted so that the axis of transmission is

above the maximum mat erial level by at least the blanking

. Use a PVC coupling and nipple as provided.

. Hand tightening of the mounting hardware is sufficient.

perpendicular to the liquid surface. Avoid aiming into vortexes.
On

solids applications

, the Milltronics Easy Aimer should be used to facilitate aiming of the

transducer. Refer to the Easy Aimer instruction manual.
Where the transducer is mounted to a standpipe, the

inner standpipe surface and end must be

smooth and free of burrs, ridges and seams.

Consider the optional

temperature sensor

when mounting the transducer.

MOUNTING - LIQUID APPLI CATIONS

Flexible Condu it

flexible conduit

steel channel

Bracket

1" NPT

coupling

Flexible conduit mounted transducer
should not be subjected to wind,
vibration or jarring.

PL-418 3

transducer

MOUNTING - LIQUID APPLICATIONS (co nt’d)

Blind Flange

1" NPT nipple welded to
blind flange

1" NPT
coupling

Flange, gasket and hardware
supplied by customer. Refer to
Liquid \ Applications - Standpipes.

MOUNTING - SOLI DS APPLICATIONS

Optional Easy Aimer Kit

factory assembled
flanged transducer

bol t

gaske t

nut

Flanged

1" NPT
coupling

FLAT FACE FLANGE ONLY

Customer f langed standpipe. If metal
flange must be welded to pipe, refer
to Liquid\ Applications - Standpipes.

Easy Aimer Kit

transducer

In solids applications, the transducer should be mounted so that it is aimed toward the low
level draw point. To facilitate this mounting, it is suggested that the opt ional Milltronics

Aimer Kit

be used. Refer to the Easy Aimer instruction manual.

Easy

PL-418 4

APPLICATIONS

LIQUID APPLICATIONS - STANDPIPES

In many applications, access must be made via a standpipe. In such cases, Milltronics can
provide flange mounted transducers that will readily mate to the flanged standpipe. Another
option is to hang the transducer from a blind flange.

The standpipe lengt h should b e as short and the d iameter as large as possi ble. As a rule of
thumb, the –3 dB cone of t he sound beam should not intersect the standpipe wall in
applications opening into a vessel or larger area. Otherwise, additional blanking will be
required to compensate for the interference zone created by the opening.

no addit ional blanking

no
intersection

vessel

additional blanking

flanged
transducer

transducer

sound
beam

intersects

no vessel

vessel

near blanking extension

of 150 mm (6") past end of
standpipe may be required

reflect ion at
interference
zone created by
opening

PL-418 5

LIQUID APPLICATI ONS - VOLUME

"Alternate"

"Preferred"

"Bad"

tank manufacturer’s
full level

span: corresponds to
tank manufacturer’s
empty level

tank manufacturer’s
empty level

Empty level for
"alternate" loc ation .
Below this level, ech o
would reflect away
from the transducer.

5° beam angle

rise

run

discharge

1. Beam should not detect bin bottom. If this occurs use range extension parameters
(on transceivers where available) to omit false echoes. A 5° beam angle represents a
rise : run of about 20 : 1. In most tanks, the transducer should be centered as much as
possible (without interference from inlet) for optimum reading rang e .

2. Sound beam must be perpendicular to liquid surface.
If standpipe is used, refer to Liquid Applications - Standpipes.

3. Echo has missed improperly leveled transducer.

4. When perform ing an empty or full calibration , the tank must contain its normal vapour and
be at its normal temp erature.

PL-418 6

SOLIDS APP LICATIONS - TYPICAL

Easy Aimer

bin wall seams

filling profile

emptying profile

1. Transducer angled to avoid
seams in bin wall and aimed at
discharge in order to read bin
when empty.

2. Avoid intersect ing bin wall
seams, structural members and
wall irregularities. Otherwise,
refer to transceiver manual.

discharge

4. On fluid like solids, aim
transducer perpen dicular to
material surface.

transducer

minimal angle
of repose

3. Transducer too close to material
inlet. Falling material will intersect
sound beam and cause erroneous
readings or loss of echo.

5. On dual discharge bins, aim each

transducer at the discharge point.

PL-418 7

SOLIDS APPLICATIONS - SPECIAL

STORAGE BIN WITH AGITATOR

infeed

agitator

1. Transducer should be kept away from infeed.

2. Where agitators are in use, use the Agitator Discrimination param eter on transceivers
where availabl e .

3. Transducer should be aimed away from wall projections.

DRYER - WOOD CHIPS

infeed

drag conveyor

typical low level

typical high level

1. Transducer should be mounted perpendicular to slope of wood chips.

PL-418 8