Milltronics ST-50 Series User 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
equipmentthatissimpletouse andreliableinitsoperation,withtheaimofsatisfying
our customers needs.
Milltronics 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 continually being refined 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
709 Stadium Drive
Arlington, Texas
U.S.A. 76011
Oak House
Everoak Estate
Bromyard Road
Worcester, WR2-5HP
England
Château de laSaurine
Pont de Bayeux
B.P. 6
13590 Meyreuil
Aix en Provence
France
Tel. [phone]
Fax [phone] Tel. [phone] Fax [phone] Tel. [phone] Fax [phone] Tel. [phone] Fax [phone]

ABOUT THE TRANSDUCER
The ST-50 series of transducers operates in association
with Milltronics ultrasonic level monitoring products.
The transducer converts the electrical energy of the
transmit pulse from the transceiver into acoustical energy.
It then converts the acoustical 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 inversely proportional to the square
of the distance. Maximum power is radiated axially
(perpendicular) from the transducer face in a line referred
to as the axis oftransmission. Where power is reduced by
half (– 3 dB), a conical boundary defining the sound beam,
centered about the axis of transmission is established. The
diametric measurement of the cone in degrees defines the
beam angle. Impedance matching techniques are used to
optimize the transfer of power from the transducer into air
and from the air back into the transducer.
SPECIFICATIONS
Model : » ST-50
Measurement range : » typically 0.3 m-15 m (1-50 ft) restricted to transceiver maximum▲
Temperature range : » – 40 to 93 °C (– 40 to 200 °F)✧
Frequency : » typically 44 KHz, transceiver dependent
Beam angle : » 5°
Weight* : » 3.9 Kg (8.5 lb)
Construction : » CPVC housing with polyurethane face
» 1" NPT mounting/conduit connection with neoprene jacketed cable
» totally encapsulated
» options: » flanging: the transducer can be factory flanged,
consult Milltronics
» facing: » CPVC for corrosive applications
» Teflonfor corrosive applications
» polyethylene foam for dry-dust applications
Separation : » typically 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)
Teflonis a registered trade mark of Dupont
– 3 db
boundary
5°
beam
angle
axis of
transmission,
perpendicular
to transducer
face
transducer
95/07/11
transducer
face
PL-418 1

OUTLINE AND CONNECTION
DO’S AND DON’TS
VERY IMPORTANT
Do not route cable openly in raceways.
For optimum isolation against electrical 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.
Transducer wiring must be done in conjunction with approved conduit, boxes and fittings
and to procedures in accordance with all governing regulations.
Seal all thread connections to prevent ingress of moisture.
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 elecrostatic discharge, housing (except free) must be covered with copper
mesh and grounded.
96/03/19
125 mm
(4.9")
CPVC housing
radiating surface
(see Specification \ Construction)
140 mm
(5.5") dia.
OR
shield
hot
RG62A/U
coaxialcable
direct connection
junction box
white
black
white
black
shield
Milltronics
transceiver
S
H
I
E
L
D
H
O
T
1" NPT
cable*,
PVC jacket
*Cable length: » standard: 5 m (16 ft)
» optional: consult Milltronics
PL-418 2

MOUNTING
DO’S AND DON’TS
VERY IMPORTANT
Mount the transducer so that it is above the maximum material level by at least the blanking
value
. Refer to the associated transceiver manual.
Do not mount the transducer directly to metal . Use a PVC coupling and nipple as provided.
Do not overtighten mounting . Hand tightening of the mounting hardware is sufficient.
On
liquid applications , the transducer must be mounted so that the axis of transmission is
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 Aimerinstruction 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 APPLICATIONS
steel channel
1" NPT
coupling
transducer
flexible conduit
Flexible Conduit Bracket
Flexible conduit mounted transducer
should not be subjected to wind,
vibration or jarring.
PL-418 3

MOUNTING - LIQUID APPLICATIONS (cont’d)
MOUNTING - SOLIDS APPLICATIONS
Optional Easy Aimer Kit
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 optional Milltronics
Easy
Aimer Kit
be used. Refer to the Easy Aimer instruction manual.
Customer flanged standpipe. If metal
flange must be welded to pipe, refer
to Liquid\ Applications - Standpipes.
Flange, gasket and hardware
supplied by customer. Refer to
Liquid \ Applications - Standpipes.
1" NPT
coupling
nut
Flanged
Blind Flange
1" NPT nipple welded to
blind flange factory assembled
flanged transducer
FLATFACE FLANGEONLY
gasket
bolt
1" NPT
coupling
transducer
Easy Aimer Kit
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 length should be as short and the diameter as large as possible. As a rule of
thumb, the –3 dB cone of the 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 additional blanking
transducer
sound
beam
intersects
vessel
near blanking extension
of 150 mm (6") past end of
standpipe may be required
reflection at
interference
zone created by
opening
no
intersection
vessel
additional blanking
flanged
transducer
no vessel
PL-418 5

LIQUID APPLICATIONS - VOLUME
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 range.
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 performing an empty or full calibration, the tank must contain its normal vapour and
be at its normal temperature.
tank manufacturer’s
empty level
rise
Empty level for
"alternate" location.
Belowthis level, echo
would reflect away
from thetransducer.
span: corresponds to
tank manufacturer’s
empty level
tank manufacturer’s
full level
"Alternate" "Preferred" "Bad"
discharge
5° beam angle
run
PL-418 6

SOLIDS APPLICATIONS - TYPICAL
transducer
minimalangle
of repose
discharge 5. On dual dischargebins, aim each
transducer at the discharge point.
4. On fluid likesolids, aim
transducer perpendicular to
material surface.
bin wallseams
fillingprofile
emptyingprofile
3. Transducertoo close to material
inlet. Falling material will intersect
sound beam and cause erroneous
readings or loss of echo.
1. Transducer angled to avoid
seams in bin wall and aimed at
dischargein order to read bin
when empty.
2. Avoid intersecting bin wall
seams, structuralmembers and
wall irregularities. Otherwise,
refer to transceiver manual.
Easy Aimer
PL-418 7

SOLIDS APPLICATIONS - SPECIAL
STORAGE BIN WITH AGITATOR
1. Transducer should be kept away from infeed.
2. Where agitators are in use, use the Agitator Discrimination parameter on transceivers
where available.
3. Transducer should be aimed away from wall projections.
DRYER - WOOD CHIPS
1. Transducer should be mounted perpendicular to slope of wood chips.
agitator
typical high level
typical low level
drag conveyor
infeed
infeed
PL-418 8