spinning disk manual

C O P Y R I G H T © 2 0 1 7 D R O P L E T M E A S U R E M E N T T E C H N O L O G I E S

Spinning Disk

Calibrator

For use with the CIP, CCP, CAPS,

MPS, PIP and OAP

Operator Manual

DOC-0012 Revision D

2400 Trade Centre Avenue

Longmont, CO 80503 USA

Spinning Disk Manual

DOC-0012 Rev D i i

© 2017 DROPLET MEASUREMENT TECHNOLOGIES

2400 TRADE CENTRE AVENUE

LONGMONT, COLORADO, USA 80503

TEL: +1 (303) 440-5576

FAX: +1 (303) 440-1965

WWW.DROPLETMEASUREMENT.COM

In no event will Droplet Measurement Technologies, LLC (DMT) be liable for direct, indirect, special,

incidental or consequential damages resulting from any defect or omissions in this manual.

DMT reserves the right to make changes to this manual and the products it describes at any time,

without notice or obligation. Revised editions are found on the manufacturer’s website.

All DMT product names and the Droplet Measurement Technologies Logo are trademarks of Droplet

Measurement Technologies, LLC.

All other brand and product names are trademarks, or registered trademarks, of their respective owners.

Software License

DMT licenses its software only upon the condition that you accept all of the terms contained in this

license agreement.

This software is provided by DMT “as is” and any express or implied warranties, including, but not limited

to, the implied warranties of merchantability and fitness for a particular purpose are disclaimed. Under

no circumstances and under no legal theory, whether in tort, contract, or otherwise, shall DMT or its

developers be liable for any direct, indirect, incidental, special, exemplary, or consequential damages

(including damages for work stoppage; computer failure or malfunction; loss of goodwill; loss of use, data

or profits; or for any and all other damages and losses). Some states do not allow the limitation or

exclusion of implied warranties and you may be entitled to additional rights in those states.

Warranty

The seller warrants that the equipment supplied will be free from defects in material and workmanship

for a period of eighteen months from date of shipment or 12 months from the date of either installation

or first use whichever comes first. When returning the equipment to DMT for warranty or service

procedures, the equipment owner will pay for shipping to DMT, while DMT will pay the return shipping

expense. Consumable components, such as tubing, filters, pump diaphragms, and Nafion humidifiers and

dehumidifiers are not covered by this warranty.


DOC-0012 Rev D i i i


Laser Safety Information

The spinning disk unit used with DMT’s CIP, CCP, CAPS, MPS and PIP probes does not contain a

laser, but all of these probes themselves contain class IIIB lasers. AVOID DIRECT EXPOSURE TO THE

BEAM. Observe laser safety precautions and wear appropriate laser safety glasses. Avoid placing

reflective materials in the beam that could redirect the beam, including watch bands, rings or tools.

See additional safety information in the probe instruction manual.

STRICT OBSERVANCE OF THE FOLLOWING WARNING LABELS IS ADVISED.

CAUTION Never operate the disk without the protective shroud and cover in place.

Do not operate above the specified 5000rpm.

Operate at your own risk: DMT is not responsible for damage or injury due to

improper use.

CAUTION AVOID EXPOSURE TO

SCATTERED LASER

RADIATION AND

BRIGHT DISCHARGES


DOC-0012 Rev D i v


C O N T E N T S

1.0 Introduction ...................................................................................................... 6

1.1 Specifications ......................................................................................................................... 7

2.0 Installation and Operation ................................................................................. 8

3.0 Aligning the Spinning Disk ............................................................................... 11

3.1 Off-Center Images ............................................................................................................... 12

3.2 Tilted Images ....................................................................................................................... 14

3.3 Elongated or Shortened (Rather than Round) Images ........................................................ 15

4.0 Interpreting Results ......................................................................................... 16

5.0 Removing and/or Changing the Glass Disk ....................................................... 16

5.1 Removing the Glass Disk...................................................................................................... 16

5.2 Inserting a Glass Disk ........................................................................................................... 17

6.0 Cleaning the Disk ............................................................................................. 18

Appendix A: PIP Spinning Disk ....................................................................................... 19

Appendix B: MPS Spinning Disk ..................................................................................... 20

Appendix C: Symbols Spinning Disk ............................................................................... 21

Appendix D: Revisions to Manual .................................................................................. 22


DOC-0012 Rev D v


Figures

Figure 1: Glass Pattern for CIP, CCP, CAPS and MPS Disks (Not to Scale) ........................... 7

Figure 2: Spinning Disk Base, Disk Unit, and Installation Screws ....................................... 8

Figure 3: Clamp Knob on Spinning Disk Base .................................................................... 9

Figure 4: Spinning Disk Installed on a CIP ....................................................................... 10

Figure 5: Images Generated by a Properly Aligned Spinning Disk ................................... 11

Figure 6: Off-Edge Images ............................................................................................. 12

Figure 7: Adjusting the Disk-Alignment Screw ............................................................... 13

Figure 8: Tilted Images .................................................................................................. 14

Figure 9: Elongated Droplet Images (Oversampling); Airspeed is too Fast ...................... 15

Figure 10: Shortened Droplet Images (Undersampling); Airspeed is too Slow ................. 15

Figure 11: Removing Disk Housing Cover ....................................................................... 16

Figure 12: Unscrewing the Glass Disk ............................................................................ 17

Figure 13: Inserting a Disk ............................................................................................. 17

Figure 14: Particle Images from a Dirty Disk .................................................................. 18

Figure 15: Particle-Count Histogram generated by Dirty Disk. Note Large amount of small

particles. ................................................................................................................ 18

Figure 16: Spinning Glass Disk Pattern for the PIP .......................................................... 19

Figure 17: Spinning Disk Installed on a PIP ..................................................................... 20

Figure 18: Spinning Disk installed on an MPS ................................................................. 20

Figure 19: Symbols Disk Pattern .................................................................................... 21


DOC-0012 Rev D 6


1.0 Introduction

The Droplet Measurement Technologies (DMT) spinning disk calibrator is used to simulate particles

passing through the beam of several DMT instruments: The Cloud Imaging Probe (CIP), the Cloud

Combination Probe (CCP), the Cloud, Aerosol, and Precipitation Spectrometer (CAPS), the

Meteorological Particle Spectrometer (MPS), the Precipitation Imaging Probe (PIP), and older 1D

and 2D OAPs. Within the following discussion, these are all referred to as the “instrument.” The

spinning disk calibrator is referred to as the “spinning disk.”

The spinning disk consists of a glass disk with two-dimensional, opaque images on it that are

rotated through the laser beam of the instrument. These images are most often circular, like

particles,1 and they produce shadow images that are nearly identical to spherical droplets of the

same size. Thus, the spinning disk is a useful and valid calibration device.

The spinning disk can be used for troubleshooting, since it provides a steady source of particles to

the probe and exercises the complete optical and electrical systems of the instrument. In addition,

the spinning disk can be used as an end-to-end confidence check prior to a data collection

campaign.

1 Some glass disks have different symbols to test particle-imaging software. See Appendix B.


DOC-0012 Rev D 7


1.1 Specifications

Power: 115/230 VAC 50-60 Hz.

Rotation Rate: 5000 rpm

Particle Sizes2: 50 μm, 125 μm, 250μm, 500μm, 1000μm, 2000μm

Dot Speed: 25m/s (approximately)

Figure 1 shows the spinning disk pattern for a CIP, CCP, CAPS, and MPS. For a PIP disk, see Appendix

A.

Figure 1: Glass Pattern for CIP, CCP, CAPS and MPS Disks (Not to Scale)

2 These sizes vary for instruments other than a standard CIP. See Appendix A.


DOC-0012 Rev D 8


2.0 Installation and Operation

The spinning disk arrives in a padded case that contains the disk unit, the mounting base, a power

cord, and installation tools. To install the unit, follow the steps below. Make sure to follow the

necessary laser safety precautions for the instrument and AVOID DIRECT EXPOSURE TO THE BEAM.

1.) Position the base so the silver side is facing upward. Attach the disk unit to the base using

the two hex screws and the provided 5/64” hex driver. See Figure 2.

Figure 2: Spinning Disk Base, Disk Unit, and Installation Screws


DOC-0012 Rev D 9


2.) Loosen the black clamp knob (Figure 3) on the base until the base comes apart lengthwise

in two halves. Mount the spinning disk on the instrument. The disk fits over the two CIP

arms, as shown in Figure 4, and should be centered between these arms. On the PIP, it fits

over the cross-arm, as illustrated by Figure 17 in Appendix A. On the MPS, it is positioned

between the two arms of the instrument, as shown in Figure 18 of Appendix B.

3.) Remove the dust cap that covers the circular window on the disk. Position the disk so that

the laser beam will intercept the window.

Figure 3: Clamp Knob on Spinning Disk Base


DOC-0012 Rev D 1 0


Figure 4: Spinning Disk Installed on a CIP

4.) Tighten the black knob to secure the spinning disk to the instrument.

5.) Turn on the instrument and data system.

6.) Turn on the spinning disk by attaching the power cord to the instrument and applying power.


DOC-0012 Rev D 1 1


3.0 Aligning the Spinning Disk

The spinning disk must be properly aligned, as results generated by a poorly aligned disk may falsely

suggest the instrument needs calibration. An aligned disk will generate images like those shown in Figure

5. Images will appear as circles and will be relatively centered in the display columns.

Figure 5: Images Generated by a Properly Aligned Spinning Disk

Often, however, images do not look like this when the spinning disk is first installed. The following

sections provide instructions on adjusting the disk based on specific image problems.


DOC-0012 Rev D 1 2


3.1 Off-Center Images

At times the images will appear be off the edge of the display screen, as in Figure 6. This is caused

by the images on the disk not being centered in the beam.

Figure 6: Off-Edge Images

To fix this issue, adjust the disk-alignment screw as shown in Figure 7. This will move the images left

or right and center them in the beam.


DOC-0012 Rev D 1 3


Figure 7: Adjusting the Disk-Alignment Screw


DOC-0012 Rev D 1 4


3.2 Tilted Images

Images may also appear tilted, as in Figure 8. This problem occurs when the particle images are

passing through the beam at an angle.

Figure 8: Tilted Images

To fix this issue, raise or lower the spinning disk by loosening the base, repositioning the device,

and tightening it again. On the CIP, the black tabs may no longer rest on the cross-arm (as shown in

Figure 4) after such an adjustment.


DOC-0012 Rev D 1 5


3.3 Elongated or Shortened (Rather than Round) Images

Elongated images (Figure 9) indicate an oversampling error, which arises when airspeed is too fast.

Shortened images (Figure 10) indicate under sampling, which occurs when airspeed is too slow.

Airspeed can be adjusted manually from the Setup tab in the PADS system. This adjustment should

fix the image display. 25 m/sec is a good starting value for airspeed when using the spinning disk.

Figure 9: Elongated Droplet Images (Oversampling); Airspeed is too Fast

Figure 10: Shortened Droplet Images (Under sampling); Airspeed is too Slow


DOC-0012 Rev D 1 6


4.0 Interpreting Results

After the spinning disk has been aligned, use the histogram display to see particle counts as a

function of size. The spinning disk should produce a narrow distribution of counts around several

size classes, depending upon the type of instrument. See your instrument’s Calibration Data Report

for a comparison to that Instruments’ proper sizing. If the peaks are wide or are not centered

properly on the class sizes, or differ greatly from the original Calibration Data Report, contact DMT

for information on calibrating the instrument.

5.0 Removing and/or Changing the Glass Disk

5.1 Removing the Glass Disk

Occasionally the glass disk must be removed for cleaning or for substitution of a new disk. It is best

to remove the disk in an environment as free of dust as possible. Follow the instructions below.

1.) Remove the dust cover. The dust cover covers the circular window in the disk (Fig. 11).

2.) Unscrew the four screws (Fig. 11) using a 5/64” hex driver.

Figure 11: Removing Disk Housing Cover

3.) Remove the black circular top of the disk housing.

4.) Locate the hole on the rim of the disk housing. Look through this hole toward the center of the unit. With your fingers on the center of the glass disk, rotate the disk until a set screw hole appears in the center of the unit. See (Fig. 13). This screw secures the disk to the motor shaft.


DOC-0012 Rev D 1 7


Figure 12: Unscrewing the Glass Disk

1.) Using a .050” Allen wrench, loosen the screw (Fig. 12)

2.) Rotate the disk until you see another screw hole. Loosen this screw as well.

3.) Remove the glass disk.

5.2 Inserting a Glass Disk

To insert a disk, hold it by its edges. Slip the disk on to the motor shaft as shown in (Fig. 13).

Figure 13: Inserting a Disk


DOC-0012 Rev D 1 8


Using a .050” Allen wrench, tighten the two screws that secure the glass disk to the motor shaft.

See (Fig. 12). The circular metal hub of the motor shaft should protrude slightly from the glass disk

surface. Next, reinstall the disk housing cover (Fig. 11) and tighten the four screws that hold the

cover in place.

6.0 Cleaning the Disk

If the disk generates images that are not clean circles (Fig. 14), or if the particle-count distribution

shows high “valleys” in between the first two particle peaks (Fig. 15), then the glass disk may

require cleaning.

Figure 14: Particle Images from a Dirty Disk

Figure 15: Particle-Count Histogram generated by Dirty Disk. Note Large number of small particles.


DOC-0012 Rev D 1 9


To clean the disk, follow the steps below.

1. Remove the glass disk as described in section 5.0.

2. Being careful to touch only the edge of the glass, clean the disk with alcohol and optical

wipes.

3. Blow the disk dry with clean air.

4. Replace the disk on the motor shaft and reinstall the cover.

Appendix A: PIP Spinning Disk

Figure 16: Spinning Glass Disk Pattern for the PIP


DOC-0012 Rev D 2 0


Figure 17: Spinning Disk Installed on a PIP

Appendix B: MPS Spinning Disk

Figure 18: Spinning Disk installed on an MPS


DOC-0012 Rev D 2 1


Appendix C: Symbols Spinning Disk

An optional symbol glass disk is available for testing of image pattern recognition software. This

disk can be inserted into the spinning disk used for any optical imaging probe. The disk contains 15

images sets in sizes, nominally 700-micron, 1800 micron and 4000-micron image widths. The

following images are present in clockwise order.

• DMT (letters)

• circle

• triangle

• square

• rectangle (8:1 aspect ratio across radius)

• rectangle (8:1 aspect ratio along radius)

• column crystal

• capped column crystal

• needle (orientation 1)

• needle (orientation 2)

• bullet

• star (six pointed)

• bullet rosette

• hexagonal plate

• dendrite

Figure 19: Symbols Disk Pattern


DOC-0012 Rev D 2 2


Appendix D: Revisions to Manual

Rev. Date Rev. No. Summary Section

2/26/10

B

Added installation instructions for mounting on CIP

and PIP

2

Expanded calibration section 3

Inserted pictures All

Added laser safety warnings Front, 2

Added symbols disk pattern Appendix C

11/30/10 C Added installation instructions for mounting on a PIP Appendix B

11/6/12 C-1 Updated disk pattern diagram to reflect new sizes Figure 1

4/12/13 C-2 Updated PADS histogram to reflect new sizes and

new version of PADS

Figure 5

11/25/14 C-3 Updated histograms with new Graphics Multiple

2/5/17 D Updated missing figure 11 with See Cal sheet Section 4

spinning disk manual

Documents