Campbell UT20 User manual

Revision: 03/2020
Copyright © 1993 – 2020
Campbell Scientific, Inc.

Table of contents
1. Introduction 1
2. Precautions 1
2.1 Site selection 1
2.2 Tower mounting 1
2.3 Tower installation 2
3. Initial inspection 2
3.1 Indoors 2
3.2 Outdoors 2
3.3 Tools required 3
4. Siting and exposure 3
4.1 Wind speed and direction 4
4.2 Temperature and relative humidity 4
4.3 Precipitation 5
4.4 Solar radiation 5
4.5 Soil temperature 6
4.6 Siting references 6
5. Overview 6
6. Specifications 8
7. Tower installation 9
7.1 Installing the tower 9
7.1.1 Base and Guy Anchor Layout 10
7.1.2 Tower base installation 11
7.1.2.1 UTBASE base installation 11
7.1.2.2 RFM18 base installation 20
7.1.3 Guy anchor installation 21
7.1.3.1 UTEYE eyebolt guy anchor 21
7.1.3.2 UTDUK duckbill guy anchor 22
7.1.4 Tower assembly 24
7.1.5 UTGND tower grounding kit 26
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7.1.6 Attaching the lightning rod 28
7.2 Crossarms and mounting brackets 29
7.2.1 CM202, CM203, CM204, CM206 Crossarms 29
7.2.2 CM230, CM230XL adjustable angle mounting kits 30
7.2.3 CMB200 crossarm brace kit 32
7.2.3.1 Components 33
7.2.3.2 Assembly 34
Appendix A. UTBASE paper template 37
Paper template, page 1 38
Paper template, page 2 39
Paper template, page 3 40
Table of Contents - ii

1. Introduction
The UT20 and UT30 are durable, lightweight instrument towers used for a variety of applications.
They support a 6 m (20 ft) or 9 m (30 ft) measurement height for wind sensors as well as sturdy
attachment points for antennas, solar panels, environmental enclosures, radiation shields, and
crossarms. A retractable mast at the top of the tower adds increased flexibility in the placement of
sensors at the top of the tower.
NOTE:
Throughout the manual, the term "tower" refers to both the UT20 and UT30, unless specified
otherwise.
2. Precautions
2.1 Site selection
lSelect a safe site to install the tower.
lThe distance between any power lines and the installation site should be at least one and
one-half times the height of the tower. Make the distance even greater, if possible. Since
all overhead lines look somewhat alike, consider them all dangerous and stay well away
from them.
lIf there are power lines or buried utilities in the area, call the local utility providers for
assistance.
2.2 Tower mounting
lNEVER work alone; always have someone near who can summon help.
lCertain clothing may provide a degree of safety, but do not depend on it alone to preserve
life (for example, rubber boots or shoes, industrial rubber gloves, or a long shirt or jacket).
lCheck local weather conditions. Be sure it has not rained recently, and the ground is not
wet or muddy. Make sure rain or thunderstorms are not predicted for the day the tower is
to be installed.
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lTo avoid having the tower being blown into nearby power lines, do not install or remove
towers in moderate or heavy winds.
lIf it is necessary to use a ladder, choose a ladder made of non-conductive, non-metallic
materials.
lHave someone present who has been trained in electric shock first aid, if possible.
2.3 Tower installation
lProperly assemble the tower according to the instructions in this manual (do this in the
location the tower is to be installed).
lOnce the tower is in its full vertical position, securely fasten the tower to the base.
lGround the tower in accordance with all applicable local electrical codes.
lKeep the bottom of the tower legs free of soil, ice, and debris to prevent trapping any
moisture inside or around the tower legs.
3. Initial inspection
3.1 Indoors
Immediately upon receipt of the tower:
lInspect the shipping cartons for visible damage. Report any damage to the shipping
company.
lOpen all shipping cartons.
lCheck the contents of the cartons against the invoice. Contact Campbell Scientific
immediately if any parts are missing.
3.2 Outdoors
lLocate a suitable site for the tower (Siting and exposure (p. 3)).
lPrepare the tower base (Tower installation (p. 9)).
oInstall sensors to be mounted above a height of 3 m.
oRaise the tower (Tower installation (p. 9)).
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oInstall the instrumentation enclosure (Tower installation (p. 9)).
oInstall sensors to be mounted below a height of 3 m.
3.3 Tools required
Tools required to install and maintain a Campbell Scientific tower:
lShovel
lRake
lOpen end wrenches: 3/8 in, 7/16 in, 1/2 in, (2) 9/16 in
lSocket wrench set
lMagnetic compass
lTape measure
lNut driver (3/8 in)
lLevel
lSledgehammer
lPliers
lStraight bit screwdrivers
lPhillips screwdrivers
4. Siting and exposure
DANGER:
If any part of the weather station comes into contact with power lines, death or serious injury
could occur. Contact local utilities for the location of buried utility lines before digging or
driving ground rods.
Selecting an appropriate site for the weather station is critical to obtain accurate meteorological
data. In general, the site should be representative of the area being studied, and away from the
influence of obstructions such as buildings and trees.
Do not place the weather station where sprinkler irrigation water will strike the sensors or
instrument enclosure.
The general guidelines for site selection given here were condensed from these sources: EPA
(2000)1, WMO (2010)2, and AASC (1985)3.
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4.1 Wind speed and direction
As specified by the EPA1, wind sensors should be located over open, level terrain at a distance at
least ten times the height of any nearby buildings, trees, or other obstructions as shown in
FIGURE 4-1 (p. 4).
Standard measurement heights:
l3.0 m ± 0.1 m recommended (AASC)
l2.0 m ± 0.1 m, 10.0 m ± 0.5 m optional (AASC)
l10.0 m (WMO and EPA)
FIGURE 4-1. Effect of a structure on wind flow
4.2 Temperature and relative humidity
Sensors should be located over an open, level area at least 9 m (EPA1) in diameter. The surface
should be covered by short grass, or, where grass does not grow, the natural earth surface. Locate
sensors at a distance of at least four times the height of any nearby obstructions and at least 30 m
(EPA1) from paved areas. Sensors must be protected from thermal radiation and adequately
ventilated.
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Situations to avoid include:
lIndustrial heat sources
lRooftops
lSteep slopes
lSheltered hollows
lTall vegetation
lShaded areas
lSwamps
lAreas where snow drifts occur
lLow places holding standing water after rainstorms
Standard measurement heights:
l1.5 m ± 1.0 m (AASC)
l1.25 to 2.00 m (WMO)
l2.0 m temperature (EPA)
l2.0 m and 10.0 m for temperature difference (EPA)
4.3 Precipitation
Rain gages must be sited on level ground covered with short grass or gravel. In open areas,
choose a site where the distance to any obstruction is two to four times (EPA, AASC) the height
of the obstruction.
Position the height of the opening as low as possible, but high enough to avoid splashing from
the ground. Wind shields, such as Campbell Scientific 260 953 Alter-Type Rain Gage Wind
Screen, are recommended for open areas.
When necessary, use heated collectors to properly measure frozen precipitation. The gage must
be mounted above the average level of snow accumulation in areas that experience significant
snowfall.
Standard measurement heights:
l1.0 m ± 1.0 cm (AASC)
l30.0 cm minimum (WMO, EPA)
4.4 Solar radiation
Mount pyranometers in locations that avoid shadows on the sensor at any time. Mounting the
sensor on the southernmost (Northern Hemisphere) portion of the weather station will minimize
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the chance of shading from other weather station structures. Reflective surfaces and sources of
artificial radiation must be avoided.
Heated pyranometers, such as the SP230-L from Campbell Scientific, are available for use in areas
where snow, frost, or dew may accumulate.
The height the sensor is mounted is not critical.
4.5 Soil temperature
Prepare a site for soil temperature measurements at least 1 m2 and typical of the surface of
interest. The ground surface must be level to the immediate area (10 m radius).
Standard measurement depths:
l10 cm ± 1.0 cm (AASC)
l5.0 cm, 10.0 cm, 50.0 cm, 100.0 cm (WMO)
4.6 Siting references
1EPA, (2000). Meteorological Monitoring Guidance for Regulatory Modeling Applications, DPA-
454/R-99-005. Office of Air Quality Planning and Standards, Research Triangle park, NC. 27711
2WMO, (2008 edition, updated in 2010). Guide to Meteorological Instruments and Methods of
observation. World Meteorological Organization No 8, 2008 edition, Geneva Switzerland.
3The State Climatologist, (1985). Publication of the American Association of State Climatologists:
Height and Exposure Standards for Sensors on Automated Weather Stations, v. 9, No. 4, October
1985.
5. Overview
The UT20 and UT30 towers provide a versatile mount for sensors, antennas, solar panels,
environmental enclosures, radiation shields, and mounting crossarms. Its 6 m (20 ft) or 9 m (30 ft)
height allows for wind measurements at those levels.
The main tower frame (FIGURE 5-1 (p. 7)) is built from 2.5 cm (1 in) OD (outside diameter)
corrosion-resistant aluminum tubing. It includes an adjustable mast, a hinged base, anchor bolts,
lightning rod, ground rod, and cable tie kit.
Enclosures purchased for use with this tower must be ordered with the tower mount option. This
provides the necessary bracketing to mount the enclosure to the tower.
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FIGURE 5-1. UT20 tower
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