Provisional Flat Plate Solar

Collector Testing Procedures:

First Revision

David Waksman

Elmer R. Streed

Thomas W. Reichard

Louis E. Cattaneo

Center For Building Technology

National Engineering Laboratory

National Bureau of Standards

Washington, D.C. 20234

June 1978

Prepared for Department of Energy

Office of Conservation and

Solar Applications

Washington, D.C. 20545

n c —100

U56

78 -1305A

ftefieiifii ef slaadarsS3 APR 17 1379

NBSIR 78-1305A

Supersedes NBSIR 77-1305

PROVISIONAL FLAT PLATE SOLAR

COLLECTOR TESTING PROCEDURES:

FIRST REVISION

David Waksman

Elmer R. Streed

Thomas W. Reichard

Louis E. Cattaneo

Center For Building Technology

National Engineering Laboratory

National Bureau of Standards

Washington, D.C. 20234

June 1978

Prepared for Department of Energy

Office of Conservation and

Solar Applications

Washington, D.C. 20545

V') 6; [fXblQ I

r /< ' jriO'ZA

U.S. DEPARTMENT OF COMMERCE, Juanita M. Kreps, Secretary

Dr. Sidney Harman, Under Secretary

Jordan J. Baruch, Assistant Secretary for Science and Technology

NATIONAL BUREAU OF STANDARDS, Ernest Ambler, Director

PREFACE

This document is the first revision to NBSIR 77-1305, "Provisional Flat Plate

Solar Collector Testing Procedures."* The changes made reflect the many

comments received as of May 1978.

Many of these testing procedures contained herein are developmental and will

be evaluated during a collector testing program being sponsored by the

Department of Energy (see Appendix C of this report) . Revisions or deletions

will be made as more experience is gained and inputs are received from

appropriate industry representatives, testing laboratories, designers, etc.

Many of the procedures given in this report are intended for use as a supplement to engineering analysis and would ordinarily be performed only when such

analysis is not feasible, e.g. with some innovative designs.

Comments concerning these tests are invited and should be addressed to:

Chief, Solar Criteria and Standards Program

National Bureau of Standards

Building 225, Room A-114

Washington, D.C. 20234

* "Provisional Flat Plate Solar Collector Procedures," September 1977, NBS

Report No. NBSIR 77-1305, Available from NTIS, Order No. PB 272 500.

l
ACKNOWLEDGMENTS

This report is a first revision to NBSIR 77-1305 which was prepared by the

Solar Energy Program Team of the National Bureau of Standards, Center for

Building Technology, Washington, DC, with the assistance of the Solar Energy

Systems Division of Wyle Laboratories, Huntsville, Alabama. Contributors

to the NBSIR 77-1305 document included:

Wyle Laboratories: National Bureau of Standards:

David R. Reese

Howard H. Yen

Joe H. Johnson

Robert E. Losey

Wayne L. Swanson

Rick E. Pitman

Janet M. Kennedy

David Waksman

Elmer R. Streed

Thomas W. Reichard

Edgar V. Leyendecker

Louis E. Cattaneo

Larry W. Masters

William D. Walton

The authors of this report would like to thank the many individuals and

organizations, representing the solar industry, standards organizations,

professional societies, and testing laboratories for their helpful comments.

ii
TABLE OF CONTENTS

Page

1.0 INTRODUCTION 1

2 . 0 GENERAL 2

2.1 Purpose 2 2.2 Applicability 2 2.3 Test and Evaluation Methods 2 2.4 Rating Criteria 2

3.0 SELECTION AND CHARACTERIZATION OF TEST SPECIMENS 3

3.1 Criteria 3 3.2 Identification 3 3.3 Materials 3 3.4 Specifications 3 3.5 Drawings/Manuals 4

4.0 RECEIVING INSPECTION 5

4.1 Damage Inspection 5 4.2 Documentation Compliance Inspection 5 4.3 Specimen Rejection 5

5.0 RECOMMENDATIONS FOR TEST SEQUENCING 6

6.0 DOCUMENTATION REQUIREMENTS 7

6.1 General 7 6.2 Instrumentation Calibration Records 7 6.3 Test Data 7 6.4 Final Report 8

7.0 TEST METHODS 9

7.1 Thermal Performance Test 9 7.2 No-Flow 30-Day Degradation 11

7.3 Thermal Shock/Water Spray Test 15

7.4 Thermal Shock/Cold Fill 16

7.5 Rain Test 17

7.6 Thermal Cycling 22

7.7 Positive Live Loads 25

7.8 Negative and Combination Wind Loads 29

7.9 Longitudinal Loads 34

7.10 Hail Loads 39

7.11 Air Collector Rupture and Collapse 42

7.12 Static Pressure Leakage Test 44

7.13 Fire Tests 48

8.0 REFERENCES 50

APPENDIX A - PROPOSED RATING CRITERIA FOR FLAT PLATE

SOLAR COLLECTORS A-l

APPENDIX B - CALCULATION OF ALL-DAY SOLAR COLLECTOR EFFICIENCY B-l

APPENDIX C - THE DOE COLLECTOR TESTING PROGRAM C-l

iii
SI CONVERSION UNITS

In view of the present accepted practice in this country for building

technology, common U.S. units of measurement have been used throughout this

document. In recognition of the position of the United States as a signatory

to the General Conference of Weights and Measures, which gave official status

to the metric SI system of units in 1960, assistance is given to the reader

interested in making use of the coherent system of SI units by giving

conversion factors applicable to U.S. units used in this document.

LENGTH

1 in. = 0.0254 meter (exactly)

1 ft = 0.3048 meter (exactly)

AREA

. 2 -4 2

1 in. = 6.45 x 10 meter

1 ft 2 = 0.09290 meter 2

VOLUME

1 in? = 1.639 x 10 5 meter 3

1 gal. (U.S. liquid) = 3.785 x 10

-3

meter 3

MASS

_2

1 ounce-mass (avoirdupois) = 2.835 x 10 kilogram

1 pound-mass (avoirdupois) = 0.4536 kilogram

PRESSURE OR STRESS (Force/Area)

1 inch of mercury (60°F) = 3.377 x 10 3 pascal

2 3 1 pound-force/inch (psi) = 6.895 x 10 pascal

2 5 1 pound-force/foot (psf) = 9.930 x 10 pascal

ENERGY

1 foot-pound-force (ft-lbf) = 1.356 joule

1 BTU (International Table) = 1.055 x 10 3 joule

POWER

7 1 Watt = 1 x 10 erg/second

1 BTU/hr = 0.2931 Watt

TEMPERATURE

t°C = 5/9 (t°F - 32)

HEAT

1 BTU*in./hr *ft 2 * °F = 1.442 x 10

-1

W/m*K

(thermal conductivity)

1 BTU/lbm*°F = 4.187 x 10 3 J/kg«K (specific heat)

1 langley = 4.184 x 10 4 J/m2 = 1 cal/cm2 =3.69 BTU/ft 2

IV
1.0 INTRODUCTION

1 . 1 General

This document represents the first revision to NBSIR 77-1305 which

contained preliminary testing procedures for evaluation of solar

collectors. It is intended for use:

1. As the basis of a testing program to be funded by the Department

of Energy (DoE) . In this program, which is discussed in

Appendix C of this report, approximately 200 different solar

collectors will be tested per the thermal performance and 30-

day stagnation tests presented in Sections 7.1 through 7.4 of

this document. The other tests presented in this document

which are considered to be tentative and in need of confirmation or modification will be conducted on approximately 25

different types of collectors selected to be representative of

the various types of flat plate collectors currently available.

2. As a resource document in the development of collector testing

standards by consensus standards organizations.

3. As a background document by organizations developing programs

for the certification of collector performance.

The test methods contained in this report and the provisional rating

criteria presented in Appendix A are intended for use in determining

the thermal performance, and to assist in the assessment of the

safety and durability/reliability of flat plate solar collectors.

These test methods and rating criteria have been selected after the

review of over 400 accepted industry standards and parallel existent

standards where possible. They are consistent with the intent of

the U.S. Department of Housing and Urban Development (HUD) Minimum

Property Standards (MPS) [1]* and the Interim Performance Criteria

(IPC) prepared by the National Bureau of Standards (NBS) for DoE

and HUD, respectively [2 & 3] and can be used as an aid in determining compliance with these documents.

These test methods and rating criteria are preliminary and will be

evaluated during the DoE collector testing program. Revisions or deletions will be made as more experience is gained and inputs are received from appropriate industry representatives, testing laboratories, designers, etc.

*Numbers in brackets throughout this document indicate references given on Pages 50 § 51.

1
2.0 GENERAL

2 . 1 Purpose

The purpose of this document is to set forth interim test methods

for determining the performance, reliability, durability and safety

of flat plate solar collectors.

2 . 2 Applicability

The test methods contained herein apply in general only to rigid

flat plate solar collectors having the following general characteristics : 2.2.1 Multi- or single-glaze cover

2.2.2 Liquid or air single-phase heat transfer fluid

2.2.3 Single point fluid inlet

2.2.4 Single point fluid exit

2.2.5 Separate thermal storage.

However, individual test methods may be applicable to other collector

types

.

2 . 3 Test and Evaluation Methods

Test methods contained herein address the following specific areas:

a. Thermal Performance

b. Reliability/Durability

c. Structural Performance

d. Fire Safety

2 . 4 Rating Criteria

Preliminary rating criteria are presented in Appendix A for

illustrative purposes to show how these tests may be used.

2
3.0

3.1

3.2

3.2.1

3.2.2

3.2.3

3.3

3.3.1

3.3.2

3.4

3.4.1

3.4.2

3. 4. 2.1

3. 4. 2.

2

3. 4. 2.

3

3. 4. 2.

4

3. 4. 2.

5

3. 4. 2.

6

SELECTION AND CHARACTERIZATION OF TEST SPECIMENS

Criteria

The test collectors shall be randomly selected from a normal

production run and shall be typical of the product to be sold.

Identification

Each collector submitted for testing shall have permanently

affixed thereto the following:

Manufacturer's name and address.

Model name and/or number.

A serial number.

Materials

Documentation shall be submitted with each collector identifying

component materials by commercial designation or composition,

including available data to the extent possible concerning the

following

Optical and other properties per Table 2, ASHRAE Standard

93-77 [4].

Insulation and duct liner flame spread per ASTM Standard

E-84 [5]

.

Specifications

A document shall be furnished with each test specimen providing the

following information to the extent possible:

Manufacturer's recommended heat transfer fluid.*

Collector operating parameters.*

Recommended operating flow rate.*

Recommended fill rate (hot condition)

.

Recommended operating pressure limits.

Maximum* and minimum permissable no-flow temperature limitations.

Normal operating temperature range.*

Additional operating limitations.

Requested in Table 2, ASHRAE 93-77 [4]

3
3.4.3 Mounting and handling instructions.

3.4.4 Structural load limitations (e.g. design loads).

3 . 5 Drawings/Manuals

Drawings and/or manuals shall be submitted with each collector in

sufficient detail to accurately depict;

3.5.1 Collector dimensions.*

3.5.2 Cover plate dimensions and mounting details.*

3.5.3 Absorber plate details including:

a. Dimensions

b. Fluid capacity

c. Plate and fluid passage material (s)

d. Absorber coating material

Requested in Table 2, ASHRAE Standard 93-77 [4].

4
4.0 RECEIVING INSPECTION

4 . 1 Damage Inspection

Upon receipt of a collector for testing, the test laboratory will

inspect the shipping container for any visible damage.

4.1.1 Should the container show signs of damage, the Receiving

Official will document the apparent damage and photograph

it as necessary.

4.1.2 Should no apparent damage exist, the Receiving Official

will notify the Test Engineer of the specimen's arrival.

The Test Engineer will supervise the unpacking. If

damage is noted during this process, the Test Engineer

will document the damage as in Paragraph 4.1.1 above.

4 . 2 Documentation Compliance Inspection

In the event the collector has suffered no apparent shipping

damage, the Test Engineer will:

4.2.1 Verify receipt of documentation required in Section 3.0.

4.2.2 Inspect the collector to the extent possible without disassembly for compliance to drawings and specifications

required in Section 3.0.

4 .

3

Specimen Rejection

Damaged or incomplete test specimens shall be rejected and the

supplier notified.

5
5.0 RECOMMENDATIONS FOR TEST SEQUENCING

The sequencing recommendations outlined below take into account

both technical considerations such as the use of an aging sequence

to induce materials degradation prior to testing for rain leakage

and the probability that damage will not result from a test and

the collector can be used for further testing.

1. The Static Pressure Leakage Test (7. 12) should be conducted on

the test collectors prior to performing any other tests. This

is suggested both to determine the air leakage rate of air

collectors which can affect their thermal performance and to

detect leaks in liquid collectors which would make them unsuitable for further testing.

2. The thermal performance test sequence should be conducted as follows

o Preconditioning Exposure (7.1.2)

o Thermal Performance Baseline Test (7.1.3)

o No-Flow 30-Day Degradation (7.2)

+ Thermal Shock/Water Spray Test (7.3)

+ Thermal Shock/Cold Fill Test (7.4)

o Post Stagnation Thermal Performance Test (7.1.4)

The Thermal Shock/Water Spray and Thermal Shock/Cold Fill Tests

are to be conducted during the No-Flow 30-Day Degradation test.

3. The Rain Test (7.5) should be conducted on collectors that have

been subjected to the No-Flow 30-Day Degradation test in order

to assess the effects of materials degradation caused by this

test on rain leakage.

4. The Thermal Cycling (7.6), Positive Live Load (7.7), Negative

and Combination Wind Loads (7.8), Longitudinal Load (7.9), and

Hail Load (7.10) can be conducted in any order desired. However,

since the Static Pressure Leakage Test (7.12) is used to

indicate damage caused by the first four of these tests, it

should be conducted on the test specimens prior to initiating

these tests as well as during these tests as specified in the

respective test methods.

5. The Air Collector-Rupture and Collapse (7.11) can cause distortion of the collector and should be conducted towards the end

of the test sequence.

6. Finally, the Fire Test (7.13) will cause damage to the test

collectors and should , therefore, be conducted at the end of

of the test sequence utilizing undamaged collectors from the

other tests, where possible.

6
6.0 DOCUMENTATION REQUIREMENTS

6 . 1 General

Complete records shall be maintained throughout the test program

and shall be verified by signatures of the responsible parties

for each phase of the program.

All records pertaining to the test program shall be retained by

the test laboratory for a minimum period of two years after the

conclusion of testing.

6 . 2 Instrumentation Calibration Records

The test laboratory shall maintain a documented instrumentation

calibration system which assures that each instrument used to

record test data is calibrated with standards traceable to NBS

or in the case of solar insolation to National Oceanographic

and Atmospheric Administration (NOAA) . A permanent record

must be maintained of all calibrations and a recall system

employed which prevents an instrument being used after the

expiration of its calibration period.

6 . 3 Test Data

Data sheets shall be maintained and verified by signature of the

Test Engineer and the responsible Technicians. All test data

shall be recorded, including:

6.3.1 Date and time of test.

6.3.2 Test specimen identification.

6.3.3 Model, serial number and accuracy of each instrument used

to measure or record est ata.

6.3.4 Date of the last calibration of each instrument.

6.3.5 All data necessary to verify that the test was performed

in accordance with the test procedures.

6.3.6 The result of all visual observations made during and

after the test.

6.3.7 A complete description of any failures or anomalies that

occur during or as the result of testing.

7
6.4 Final Report

As a minimum, a report shall be prepared containing the following

information concerning each test:

a. Identification of test

b. Test specimen description and identification

c. Summary of results

d. Test conditions

e. Instrumentation and equipment

f. Test results

g. A complete description of any failure,

including a photograph of the failure if possible

h. A complete description of any deviation to the

test procedure, including unplanned test halts,

or of any anomaly occurring before, during or

after tests

i. Tables, graphs, charts and photographs as appropriate

j. All-day efficiency data as computed per Appendix B.

8
6.0 DOCUMENTATION REQUIREMENTS

6.1 General

Complete records shall be maintained throughout the test program

and shall be verified by signatures of the responsible parties

for each phase of the program.

All records pertaining to the test program shall be retained by

the test laboratory for a minimum period of two years after the

conclusion of testing.

The test laboratory shall maintain a documented instrumentation

calibration system which assures that each instrument used to

record test data is calibrated with standards traceable to NBS

or in the case of solar insolation to National Oceanographic

and Atmospheric Administration (NOAA) . A permanent record

must be maintained of all calibrations and a recall system

employed which prevents an instrument being used after the

expiration of its calibration period.

Data sheets shall be maintained and verified by signature of the

Test Engineer and the responsible Technicians. All test data

shall be recorded, including:

6.2 Instrumentation Calibration Records

6.3 Test Data

6.3.1 Date and time of test.

6.3.2 Test specimen identification.

6.3.3 Model, serial number and accuracy of each instrument used

to measure or record est ata.

6.3.4 Date of the last calibration of each instrument.

6.3.5 All data necessary to verify that the test was performed

in accordance with the test procedures.

6.3.6 The result of all visual observations made during and

after the test.

6.3.7 A complete description of any failures or anomalies that

occur during or as the result of testing.

7
6.4 Final Report

As a minimum, a report shall be prepared containing the following

information concerning each test:

a. Identification of test

b. Test specimen description and identification

c. Summary of results

d. Test conditions

e. Instrumentation and equipment

f. Test results

g. A complete description of any failure,

including a photograph of the failure if possible

h. A complete description of any deviation to the

test procedure, including unplanned test halts,

or of any anomaly occurring before, during or after tests

i. Tables, graphs, charts and photographs as appropriate

j. All-day efficiency data as computed per Appendix B.

8
TEST METHODS

Thermal Performance Tests

Purpose

The purpose of the thermal performance tests is to provide collector efficiency data for system design use and to provide a measure

of changes in collector performance after environmental exposure.

The thermal performance tests are performed in general accordance

with the ASHRAE Standard 93-77. A procedure for calculating allday solar collector efficiency is contained in Appendix B.

Preconditioning Exposure

Purpose

The preconditioning exposure is performed to stabilize the

collector characteristics prior to thermal performance measurements.

o This exposure shall be used in lieu of the 1500 Btu/ft ‘day (17,000

KJ/m

2

*day) three-day exposure specified in ASHRAE Standard 93-77.

Significance

The collector is exposed to environmental conditions similar to

those encountered during the actual thermal test. The exposure

conditions are intended to induce the removal of water vapor, final

curing of sealants and coatings or other factors that could result

in inconsistent thermal performance measurements. This exposure

is not intended to influence the collector durability or reliability

characteristics.

Exposure Procedure

The collector shall be located for a period of at least 24 hours

in a building, enclosure or other shaded area where the ambient

environment has a temperature in the range of 65 to 100°F (18.3 to

37.8°C) and the relative humidity does not exceed 70 percent.

During this period, heat transfer fluid heated to an inlet temperature of between 200 to 220°F (93.3 to 104. 4°C) for liquid collectors

and 170 to 190°F (76.7 to 87.8°C) for air collectors shall be

circulated through the fluid passage ways for a period of at least

8 hours. Fluid flow rates shall be comparable to those used during

thermal performance testing. The heat transfer fluid shall be

selected from the manufacturer's recommended fluids. The collector

shall remain in the same environmental conditions as specified

above until ready for mounting on the thermal test apparatus.

9
7.1.3 Thermal Performance Easeline Test

7. 1.3.1 Purpose

The thermal performance baseline measurements provide initial

collector efficiency data over a broad range of operating conditions

7. 1.3. 2 Significance

The resulting data points will be used to establish a performance

curve for comparison with a similar post-measurement made after

. the 30-day no-flow exposure. The initial performance curve will

also be used to establish values of F,, (xa) and F DUT for use in

calculating allowable variations in peak exposure conditions during

the 4-hour period described in the 30-day no-flow test.

7. 1.3.

3

Test Procedure

The collector shall be mounted and the test conducted using the

measurement conditions, sensor accuracies, data analysis and

plotting as required by ASHRAE Standard 93-77, A thermal efficiency

test at near-normal incidence shall be conducted using at least

four inlet temperatures which include one value not greater than

10 °F (5.5°C) above ambient, one value not less than 100°F (55.5°C)

above ambient with the other two inlet temperatures approximately

equally distributed between these two extremes. Four data points

shall be taken at each inlet temperature.

The thermal performance baseline test does not require incident

angle modifier, response time measurements or the 3-day preconditioning specified in ASHRAE Standard 93-77.

7.1.4 Post Stagnation Thermal Performance Test

7. 1.4.1 Purpose

This test is intended to measure the thermal performance of solar

collectors following exposure to environmental conditions similar

to those which would be expected in actual service.

7. 1.4. 2 Significance

The thermal performance measurements are performed after the 30-

day no-flow exposure described in Section 7.2 which includes thermal

shock/water spray tests and a thermal shock/cold fill test. These

exposure tests are intended to induce collector material and con- struction problems similar to those that would occur after

10
operating the collector for extended periods. The thermal performance measurements made following such environmental exposure are believed to be indicative of the characteristics of solar collectors

after long-term exposure.

7. 1.4. 3 Test Procedure

The requirements, instrumentation, apparatus and method of testing,

test procedures and computation, recorded data and test report shall

be in accordance with ASHRAE Standard 93-77, except for the preconditioning treatment.

The incident angle modifier and the time constant measurement shall

be performed as prescribed in ASHRAE Standard 93-77.

7 . 2 No-Flow 30-Day Degradation

7.2.1 Purpose

The purpose of this test is to identify in a relatively short time,

potential problems with collector materials or construction

resulting from prolonged exposure to natural environments.

7.2.2 Significance and Use

Recognizing that elevated temperature is one of the most damaging

environments, solar irradiance and ambient temperature levels have

been selected which represent typical summer conditions in most

U.S. climatic regions. These conditions will produce the temperatures that the various materials used in solar collectors (cover

plates, absorptive coatings, sealants, etc.) will experience in use. Until adequate laboratory test procedures are adopted to

insure the ability to select reliable materials and designs, an assembly level test is considered to be necessary for evaluating

collector reliability.

2 A 4-hour exposure period with a minimum flux of 300 Btu/ft *hr

2 (946 W/m ) is specified in the test method. During this exposure

period, it is intended that the collector be exposed to the normal

peak profile that it would see on a fixed mount facing South.

The test procedure does not include provisions for evaluating

tracking concentrating collectors or collectors used with external

reflectors to enhance solar radiation. Modifications to the

exposure apparatus may be necessary to accommodate these collectors

such as the addition of a reflector for flat plate collectors.

This test method will be superceded as soon as a consensus standard,

similar to the test outlined herein, is approved.

11
7.2.3 Test Specimen

The test specimen shall consist of a complete air or liquid

collector panel assembly.

7.2.4 Pre-Exposure Preparation

7. 2. 4.1 Air Collector duct openings shall be sealed to prevent cooling by

convective air flow and the entry of dirt or precipitation. The

collector shall be vented to prevent build up of pressure.

7. 2. 4.

Liquid Collectors Intended for Use in All Systems (with or without

draindown) shall be completely filled with distilled water,*

following which the inlet shall be sealed and the outlet provided

with a pressure relief valve set to a value between 0% and +10% over

the manufacturer’s recommended maximum operating pressure.

7. 2. 4.

Liquid Collectors Limited to Use in Systems that Draindown when

not Operating shall be completely filled with distilled water,*

following which the fluid shall be allowed to gravity drain for

15 minutes with the collector mounted at a 45° tilt angle. The

collector inlet shall then be protected to prevent entry of dirt

or precipitation. The collector shall also be vented to prevent

build up of pressure.

7.2.5 Exposure Conditions

7. 2. 5.1 Exposure conditions shall consist of 30 days of cumulative exposure

to a minimum daily incident solar radiation flux of 1500 Btu/ft2 -day

(17,000 KJ/m2 -day) as measured in the plane of the collector aperture

The exposure conditions shall include at least one consecutive 4-

hour period with a minimum instantaneous flux of 300 Btu/ft2 -hr**

(946 W/m2

). This exposure must occur after the collectors have

boiled dry, where applicable.

7. 2. 5.

The average baseline ambient temperature shall be 80°F (26.7°C) or higher during the 4-hour exposure period.

* Manufacturer's/designer's recommended fluid shall be used in those instances

when they specifically prohibit the use of distilled water.

** Collector orientation changes to maximize the solar radiation or supplementary reflectors may be necessary to obtain the 300 Btu/ft2

* hr (946 W/m2

) insolation level at certain locations. However, the maximum peak flux

shall not exceed 370 Btu/ft 2 (1165 W/m2

) under normal sun-sky or simulator

exposure conditions.

12
If the ambient temperature values recorded during the 4-hour exposure

period do not reach the minimum, trade-offs between insolation and

ambient temperature can be made to meet these requirements. When

these trade-offs are made, the plate temperature (t ) shall equal or

IT exceed the plate temperatures that would occur in the collector

when exposed to a daily radiation cycle on a fixed rack during the

2 2 4-hour 300 Btu/ft • hr (946 W/m ) or greater condition with an ambient

temperature of 80°F (26.7°C). The ambient temperature shall not be

less than 70°F (21.1°C) when such trade-offs are made.

The relationship between solar irradiance, ambient temperature and

plate temperature shall be calculated using the following procedure:

The collector efficiency is expressed by

n = F R

(ta) e

PR

U

L

(t i-t

a

)

( 1 )

At the condition where the efficiency, n , equals zero,

and

F

R

(xa)

e fr

u

l

( 2 )

or

F r

(

T a

)

e

t = I —- + t

P Fd Ut _ a

( 3 )

Values of F

R

(ta)

e and F R

U

L can be obtained from the intercept and

slope of the thermal performance curves established by the initial

efficiency measurements described in Section 7.1.3. The value of

F

r

U

l

is a constant for collectors conforming to a straight line

(linear) relationship between efficiency, n , and At/I.

If a second order curve is required to fit the thermal performance

data points, then the value of F R

U

L should be obtained in the

region of the last data points using the first derivative of the

2 equation for the curve. Therefore, using n = F R

U

L

[ A+BAt/I+C ( At/I ) ] the first derivative with respect to At/I is F

RU^ = +B-2CAt/I

The revised exposure conditions required to achieve an equivalent

t can then be calculated using Equation (3) as follows:

P

F

R

(t«) e

+ t a , 1 = I. F R

(Ta)

e f r

ul

+ t a , 2 (4)

13
substituting the minimum values in Equation (4) gives:

X

2 "

FR

(ta) e 300 -Tiur^ + 80 " R Li

1 F„U„

R L

F_ (ia) R e

( 5 )

and finally the irradiance required to compensate for ambient

temperature below 80°F (27°C) can be calculated by:

I

2 = 300+ 80-t

a , 2

F UR L

F

R

(ta)

e

( 6 )

7.2.6 Data Requirements

7. 2.

6.1

The exposure conditions including hourly insolation, ambient

temperature, wind velocity and daily precipitation shall be

recorded to enable determination of the average daily values.

Insolation and ambient temperature values shall be recorded every

2 2 30 minutes during the 4-hour 300 Btu/ft ‘hr (946 W/m ) minimum

flux exposure period.

7.2. 6.2 A regularly scheduled weekly visual inspection shall be made and a record of changes in the physical construction or appearance of

the collector maintained.

7. 2. 6.

3

The results of the pre-test and post-test thermal performance shall

be plotted on the same graph for comparison purposes. A written

description of observed changes in the physical or optical appearance of the collector shall be reported and substantiated with

photographs where appropriate.

14
7.3 Thermal Shock/Water Spray Test

7.3.1 Purpose

The purpose of this test is to determine the ability of a solar

collector to withstand thermal shock caused by heavy rain falling

on the heated collector.

7.3.2 Test Specimen

The test specimen shall consist of a complete air or liquid solar

collector panel assembly undergoing 30-day no-flow testing. The

inlet, outlet and vent ports not normally exposed to rain shall be

sealed. To assure that the collector has reached stagnation

temperature, the spray test shall be conducted after at least one hour of exposure to direct sun with a minimum irradiance of

2 2 270 Btu/ft .hr (850 W/m ) measured in the plane of the collector.

The test shall be conducted between the 20th and 30th exposure days.

7.3.3 Apparatus

The apparatus consists of a distilled* water-spray system designed

to provide the specified quantity of water in such a manner as to

wet the collector uniformly and to wet those areas vulnerable to

water penetration during normal exposure to rain. The temperature

of the water shall be within 75+10°F (23.9+5.5°C) during the test.

7.3.4 Procedure

2 STEP 1 - Adjust the water spray to provide not less than 1.8 gal/ft

of collector area per hour.

STEP 2 - Direct spray onto collector in such a manner as to wet

the surface that would be wet during a normal rain shower.

Maintain water spray for five (5) minutes.

STEP 3 - Turn off the water spray and dry exterior surfaces of

the collector.

STEP 4 - Inspect collector for evidence of water penetration

into the interior.

STEP 5 - Repeat Steps 1, 2, 3 and 4 on three different days.

7.3.5 Data Requirements

Document visual evidence of physical damage and water or moisture

penetration within the collector housing.

*Tap water may be used where mineral deposit buildup does not cause visual

obscuration of the cover plate.

15
7.4 Thermal Shock/Cold Fill

i

—Purpose

The purpose of this test is to evaluate the reliability of a solar

collector after being subjected to thermal shock and boiling stresses

induced by filling the hot collector with relatively cool heat

transfer fluid during daytime start-up.

7.4.2 Test Specimen

The test specimen shall consist of a complete air or liquid collector panel assembly undergoing 30-day no-flow testing. To assure

that the collector has reached stagnation temperature, the test

shall be conducted after at least one hour of exposure to direct

2 2 sun with a minimum irradiance of 300 Btu/ft *hr (946 W/m ) measured

in the plane of the collector.*

7.4.3 Apparatus

The apparatus consists of a water or air source capable of providing

the required quantity of fluid at the manufacturer's specified fill

or flow rate. The temperature of the fluid induced into the collector shall be within 75°F+10°F (23 . 9+5. 5°C)

7.4.4 Procedure

STEP 1 - Assure that the collector has reached stagnation

temperature

STEP 2 - Induce fluid flow at the manufacturer's recommended

fill or flow rate.**

STEP 3 - Maintain flow for 5 minutes.

STEP 4 - Turn off fluid flow and perform static pressure leakacre

test in accordance with Paragraph 7.12, "Static Pressure Leakage

Test .

STEP 5 - Blow out residual water (liquid collectors)

STEP 6 - Reseal inlet and outlet ports.

7.4.5 Data Requirements

Document any physical damage or leakage resulting from this test.

* Collectors that have not completely boiled out will be drained prior to

conducting this test.

**When the flow rate is not specified, a rate of 1.5 gph/ft 2 for liquidfilled collectors and 2 SCFM/ft 2 for air-filled collectors shall be used.

16
7.5 Rain Test

7.5.1 Purpose

The purpose of this test is to determine the resistance of the

solar collector to water penetration when subjected to wind-driven

rain

7.5.2 Significance and Use

The rain spray test described below as Method 1 is based upon ASTM

Standard E331 [6] which is intended for use in the evaluation of

exterior windows, curtain walls and doors. This method includes

the use of a pressure differential to enhance the penetration of

water into the assembly being tested. This type of pressure differential can occur with many types of solar collector mounting con- figurations. In the case of solar collectors that form a building

element, e.g. a roof, this pressure differential will be caused by

differences of pressure inside and outside the building. In the case of solar collectors mounted on standoffs or racks, this pressure

differential will be caused by positive and negative wind forces

acting simultaneously on opposite faces of the collector.

A second testing procedure. Method 2, included in this section is

based upon a rain penetration test, utilized by Underwriters

Laboratories [7]. This method does not include the use of a pressure differential and is included in this document for use in

the DoE collector testing program to determine whether or not it

produces results comparable to those that would be obtained with

the ASTM E331 method.

7.5.3 Test Specimen

The test specimen shall consist of a complete air or liquid

collector panel assembly.

7.5.4 Apparatus

Method 1 : The collector shall be mounted in the apparatus illustrated in Figure 1 or any arrangement of equipment capable of

performing the test procedure in a similar manner. The waterspray system shall have nozzles spaced to wet those areas vulnerable to water leakage. For additional details on construction

and calibration of the water-spray system, consult ASTM Standard

E331 [6]. The test consists of sealing the solar collector into or against one face of a test chamber, and supplying air to or exhausting air from the chamber at a rate required to maintain

17
NOTE: For a negative pressure system, the water-spray grid would be

located outside the chamber and the air supply would be

replaced by an air-exhaust system.

FIGURE 1. APPARATUS FOR RAIN TEST
the test pressure difference across the collector, while spraying

water onto the face of the collector at the required rate.

Method 2 ; The collector shall be mounted on a rack at an angle

of 45° to the horizontal. The rain test apparatus is to consist

of three spray heads mounted in a water supply rack as shown in

Figure 2. a. Spray heads are to be constructed in accordance with

Figure 2.b. The water pressure for all tests is to be maintained

at 5 psi (34.47 kPa) at each spray head. The distance between the

center nozzle and the unit is .to be approximately 3 feet (0.91 m)

.

The unit is to be brought into the focal area of the three spray

heads in such position and under such conditions that the greatest

quantity of water will enter the unit. The spray is to be directed

downward at an angle of 45° to the cover plate of the collector and

separately at an angle of 22 1/2° to the back surface of the

collector

.

7.5.5 Procedure

STEP 1 - Weigh the collector.

STEP 2 - Mount the collector in the test apparatus with the glazing

exposed to the water spray and remove any sealing material or construction that is not normally a part of the assembly as installed in or on a building. Inlet, outlet and vent ports not

normally exposed to rain shall be vented to outside the test

chamber

.

STEP 3 - Method 1 Only

o Adjust the water spray to provide a uniformly distributed spray

2 at the rate of 5.0 gph/ft over the entire collector top surface.

2 o Apply an air-pressure difference of 10 lbf/ft (1.92 inches head

of water)

.

o Maintain air-pressure difference and water spray for 15 minutes,

o Remove the air-pressure difference and stop the water spray.

Method 2 Only

o Position the spray apparatus to direct a downward spray from a distance of 3 feet at an angle of 45° with the collector cover

plate surface.

o Adjust the water pressure at each spray head to 5 psi.

o Maintain the water spray for 1 hour.

STEP 4 - Dry exterior collector surfaces and weigh the collector.

Observe and record the points of water penetration into the

collector interior.

19
ASSEMBLY 0

PLAN VIEW

WATER PRESSURE GAGE

FOR EACH SPRAY HEAD

A 28 710

B 55 1400 C 2-1/4 55 D 9 230

E 3 75

FIGURE 2A

INSERT

/3 -SQUARE SECTION SLOTS- W WIDE « G OEEP-SPACE 120*- 60* HELIX - LEADING EDGES TANGENT TO RADIAL HOLES

Item inch mm Item inch mm

A 1-7/32 31.0 N 1/32 0.80 B 7/16 11.0 P .575 14.61 C 9/16 14.0 .576 14.63 D .578 14.68 Q .453 11.51 .580 14.73 .454 11.53 E 1/64 0.40 R 1/4 6.35 F C c S 1/32 0.80 G .06 1.52 T (No. 35)

b 2.79 H (No.9)b 5.0 u (No. 40)

b 2.49

j 23/32 18.3 V 5/8 16.0 K 5/32 3.97 w 0.06 1.52 L 1/4 6.35 M 3/32 2.38

a • Molded nylon Rain-Test Spray Heads are available from Underwriters' Laboratories, Inc. b ANSI B94.ll Drill Size.

c

- Optional - To serve as wrench grip.

FIGURE 2B

FIGURES 2A and 2B. RAIN TEST APPARATUS FOR METHOD 2

20
STEP 5 Method 1 Only* o Mount the collector in the test apparatus to expose the opposite

side; or the water-spray system may be moved outside the test

chamber and a negative pressure applied in the test chamber,

o Repeat Step 3 with a water spray and air-pressure difference of

1/2 the values (2.5 gph/ft^ and 5 lbf/ft^).

Method 2 Only * Expose the collector back surface to a water spray directed downward at an angle of 22 1/2° with respect to the collector back

surface

.

STEP 6 - Repeat Step 4.

7.5.6 Data Requirements

Document any change in weight or visual evidence of water or moisture penetration resulting from the rain test.

*Applies only to collectors that are exposed to wind-driven rain on back

surface or edges.

21
7.6 Thermal Cycling

7.6.1 Purpose

The purpose of this test is to insure that solar collectors that

are intended for use in freezing conditions will perform reliably

after exposure to such conditions.

7.6.2 Significance and Use

The test is intended to induce the stresses due to differential

thermal expansion and heat transfer fluid freezing, if any, that

would occur in solar collectors when they are used in accordance

with their manufacturer's recommendations. Collectors that can be

subjected to freezing conditions according to their manufacturer

will be so tested. Similarly, collectors that are recommended for use with water when provision is made for draindown under freezing

conditions will be tested under these conditions and when fluids

other than water are recommended for use under freezing conditions,

these fluids will be used. Two alternate testing procedures are presented. The first consists of cycling the collector in a con- trolled temperature chamber. The second procedure, which is

included in this document as an alternative for use in the DoE

collector program for comparative testing purposes, consists of

thermal cycling the collector by allowing it to be cooled in a refrigerated chamber and then removing it from the chamber and

allowing it to warm up under ambient conditions. Neither of the

two test procedures are based on existent standards and should be

considered developmental in nature at the present time.

7.6.3 Test Specimen

The test specimen shall consist of a complete air or liquid collector panel assembly. The initial leakage rate of the specimen shall

be determined in accordance with Paragraph 7.12. In addition:

A. Air Collector inlets shall be equipped with a check valve

and desiccant to allow the admission of dry air, if internal

pressures of less than one atmosphere occur.

B . Liquid Collectors Intended for Use in all Systems (with or without draindown) shall be completely filled with the manufacturer's recommended fluid, following which the inlet shall be

sealed and the outlet provided with a pressure relief valve set

to a value between 0% and +10% over the manufacturer's recom- mended maximum operating pressure.

22
C. Liquid Collectors Limited to Use in Systems that Draindown When

not Operating shall be completely filled with the collector

manufacturer's recommended fluid (usually water), following

which the fluid shall be allowed to gravity drain for 15

minutes with the collector mounted at a 45° tilt angle.

D. A Temperature Sensing Device shall be installed in the collector

inlet or outlet as close to the absorber plate as possible, and

connected to a direct reading device outside the test chamber.

7.6.4 Apparatus

Method 1 : A temperature chamber capable of cycling the enclosed

temperature region from 70+10°F (21+5. 5°C) to -25°F (-32°C) at a rate of 40F° to 60F° (22C° to 33C°) per hour.

Method 2 : A temperature chamber, held at -25°F (-32°C) , capable

of cooling a solar collector placed in it at 70+10°F (21+5. 5°C)

down to -10 °F (~23°C) at a rate of 40F° to 60F° (22C° to 33C°) per

hour

7.6.5 Procedure

STEP 1 - Place the collector in the temperature chamber mounted at

the 45° tilt angle in a manner that simulates in-use constraints.

STEP 2 - Method 1 Only

o Lower the internal chamber temperature to -25°F (-32°C) at a rate

of 40F° to 60F° (22C° to 33C°) per hour and maintain until the

temperature sensor reaches -10°F (-23°C) . Lower test temperatures

should be used when specified by the collector manufacturer,

o Raise the internal chamber temperature to (70+10°F [21+5 . 5°C]

)

at a rate of 40F° to 60F° (22C° to 33 C°) per hour and maintain

until the temperature sensor reaches ambient temperature.

Method 2 Only

o Place the collector in a chamber cooled to -25°F (-32°C) and

maintain until the temperature sensor reaches -10°F (-23°C) . Lower

test temperatures should be used when specified by the collector

manufacturer

o Remove the collector from the chamber and allow it to warm up

under ambient conditions maintained at 70+10°F (21+5. 5°C)

STEP 3 - Repeat Step 2 for a total of ten (10) cycles.

STEP 4 - Perform static pressure leak test in accordance with

Paragraph 7.12 to determine structural integrity.

23
7.6.6 Data Requirements

Document

buildup

,

any visual evidence of damage, evidence of moisture

and leakage per Paragraph 7.12.

24
Positive Live Loads

Purpose

The purpose of this test is to determine the ability of a flat

plate collector to function satisfactorily after being subjected

to uniformly distributed loads resulting from snow or positive

wind pressure, whichever predominates.

Significance and Use

This test is intended to determine the capability of a rigid flat

plate collector design to safely withstand the positive loads

imposed by snow or wind pressure on the cover plate surface of the

collector and its ability to function satisfactorily following

application of such loads. This test method does not include

application of the negative wind loads on the back surface of an exposed collector.

The maximum load (Rm) to be imposed by this procedure shall be based

on the manufacturer's design load rating (U) for positive pressure

on cover plate increased by a suitable safety factor (Appendix A7).

In the absence of a manufacturer's design load rating , the maximum

load to be imposed shall be 135 psf. The maximum load of 135 psf was obtained by using a safety factor of approximately three in

conjunction with the pressure caused by a wind speed of 100 mph on

a vertical flat plate collector mounted at a height of 250 ft on a building with exposure "C" (in accordance with ANSI A-58.1 [8]).*

The selection of 100 mph wind represents the maximum expected wind

speed in the United States for a 25-year mean recurrence interval.

This test is intended to be a design qualification test and not

routinely to be performed on all collectors of a particular design.

The method is based on an established procedure ( ASTM E72) [9], but

the applicability of this procedure to flat plate solar collectors

remains to be evaluated by means of the DoE solar collector testing

program.

The method is intended for use with rigid flat plate collectors.

Its application to other types of collectors has not been determined.

*Considered as "parts or portions" on windward wall of a building.

7.7

7.7.1

25
7.7.3 Test Specimen

The test specimen shall consist of a complete air or liquid

collector unit including mounting brackets or fixtures normally

supplied with or specified by the manufacturer of the collector,

and the fixtures and fittings required to perform the "Static

Pressure Leakage Test" specified in Section 7.12.

7.7.4 Apparatus

The collector to be tested shall be mounted in the apparatus

illustrated in Figure 3. The collector shall be supported on the

test bed in accordance with the manufacturer's recommendations.

Connect with tie rods to the test bed a reaction platform wider

and longer than the area to be loaded and parallel to the face

to be loaded. The area of the collector to be loaded

shall be that surface which is exposed to wind forces, exclusive

of collector mounting brackets, if any. Place an airtight bag

(20-mil PVC plastic film or other pliable material) as wide and as long as the area to be loaded, between the specimen and the

reaction platform. Apply a load to the specimen by increasing the

air pressure in the bag. Measure the pressure with an accuracy of

2% by means of a manometer or other pressure measuring device.

7.7.5 Procedure

STEP 1 - Mount the collector in the loading apparatus such that

the glazing surface is subjected to the applied load.

STEP 2 - Determine the initial leakage rate of the collector in

accordance with Section 7.12.

STEP 3 - Apply a uniform load of 1/3 Rm at the rate of 5 psf per

minute. During application of the load, make observations of any

physical damage, noticeable deformation or distortions and note the

load at which they occur. Discontinue testing when a failure occurs.

STEP 4 - Maintain the load for a period of ten minutes and then

release the applied load.

STEP 5 - Determine the leakage rate in accordance with Section 7.12.

STEP 6 - Repeat Steps 3, 4 and 5 and increase the applied load in

increments of 1/3 Rm until some type of physical damage is observed

or a maximum of Rm is reached.

26
Tie

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27

FIGURE

3.

APPARATUS

FOR

POSITIVE

LIVE

LOAD

TEST
7.7.6 Data Requirements

The following data shall be recorded:

A. Complete description of the collector and method of

mounting to the test bed.

B. Leakage rates, initial and at end of each load cycle.

C. The maximum load applied.

D. The physical damage, distortion or other structural

problems observed during or following the test.

E. Applied load at which physical damage, distortion

or other structural problems occurred.

28
7.8 Negative and Combination Wind Loads

00

h-* Purpose

The purpose of this test is to determine the ability of a flat

plate collector to function satisfactorily after being subjected

to uniformly distributed loads resulting from either of the two

following cases. Case 1 applies when the wind has access only to

the cover plate surface of the collector and creates a suction

(negative load) on that surface. Case 2 applies when the wind has access to both surfaces of the collector and would create a combination of suction on the cover plate surface and uplift (positive

pressure) on the back surface.*

'-l 00 N> Significance and Use

This test is intended to determine the ability of a rigid, flat

plate collector design to safely withstand the uniform loads created

by either a negative wind pressure on the cover plate surface or a combination of that negative pressure with a positive wind pressure

on the back surface.

The maximum load (Rm) to be imposed by this procedure shall be the

manufacturer's design load ratings (U) for the two loading conditions increased by a suitable safety factor (Appendix A7/A8) . In

the absence of the manufacturer's design load ratings, the maximum

load to be imposed on each surface shall be 120 psf. The maximum

load of 120 psf was obtained by multiplying with a safety factor of

approximately three, the pressure caused by a wind speed of 100 mph

on a collector mounted at 45° and away from the roof edge on a 250

ft high building with exposure "C" (in accordance with ANSI A-58.1

[8]

).** The 100 mph wind speed represents the maximum expected in

the United States for a 25-year mean recurrence interval.

Although the method of applying the positive load to the back face

of the collector is based on an established procedure (ASTM E72

[9]

) these test procedures should be considered developmental at

the present time and may not be applicable when testing collectors

with corrugated, curved, or thin film glazing.

* Case 2 is applicable where the collector is mounted on an open rack or any

portion of its back surface is eight (8) inches from the mounting surface.

**Considered as "solid signs" on a roof within 1/4 h of the roof surface where

h is the height of the collector.

29
7.8.3 Test Specimen

The test specimen shall consist of a complete air or liquid

collector unit including mounting brackets or fixtures normally

supplied or specified by the manufacturer of the collector, and

the fixtures and fittings required to perform the "Static

Pressure Leakage Test" specified in Section 7.12.

7.8.4 Apparatus

The test specimen shall be mounted to the test bed in accordance

with the manufacturer's instructions and as illustrated in either

Figure 4 or Figure 5. Collectors with rigid flat glazing materials

shall be tested using Method 1 with the apparatus shown in Figure 4 Collectors which cannot be suction loaded with the equipment for

Method 1 (i.e. corrugated, curved or thin film glazings) shall be

tested using Method 2 with the apparatus shown in Figure 5. The

load measuring equipment, load cell, manometer, etc. shall

be capable of measuring the applied loads with an accuracy of 2%.

An air bag as described in Section 7.7 is placed under the specimen

to provide uplift for Case 2 tests.

Method 1 : The apparatus for Method 1, Figure 4, consists of a series of vacuum lift cups (glass handling equipment) applied to

the glazing and attached to an articulated whiffle tree

arrangement

.

Method 2 ; For Method 2, Figure 5, the apparatus consists of a vacuum chamber with the collector forming one side of the chamber

and includes a vacuum device capable of providing the required load

7.8.5 Procedure

The loads applied under these procedures are the sum of the suction

and the uplift loads for the Case 2 test and suction load only for

the Case 1 test. The suction and uplift loads are equal for the

Case 2 test.

STEP 1 - Mount the specimen to the test bed so that the glazing

surface will be lifted by the applied suction loads. For Case 2 tests, clearance must be provided for installation of the air bag

between the test bed and the specimen.

STEP 2 - Determine the initial leakage rate of the collector in

accordance with Section 7.12.

30
Crane Lift with Hydraulic Ram

NOTE: The number of suction cups shall be 2 n (where n is an integer).

FIGURE 4. METHOD 1 - APPARATUS FOR NEGATIVE LIVE LOAD TEST

(Air bag for Case 2 only)

31
£

P Cb P E o p

ra fa

<0 fa u

0) u

pu

x

•H

fa

32

FIGURE

5.

METHOD

2

-

APPARATUS

FOR

NEGATIVE

LIVE

LOAD

TEST

(Air

baqs

for

Case

2

only)
STEP 3 - Apply a load of 1/3 Rm to each surface to be tested at a rate of 10 psf per minute. For Case 2 tests this load is applied

simultaneously in both suction and uplift for a total of 2/3 Rm.

During application of the load make observations relative to any

physical damage, noticeable deformation, or distortion and note

the load at which they occur. Discontinue testing if a failure occurs

.

STEP 4 - Maintain the load for one (1) minute and then gradually

remove the load

.

STEP 5 - Determine the leakage rate of the collector in accordance

with Section 7.12.

STEP 6 - Repeat Steps 3, 4 and 5, but increase the applied load in

increments of 1/3 Rm until some type of physical damage is observed

or to a maximum of Rm. For Case 2 tests the increments shall be

1/3 Rm on each surface and the maximum shall be Rm on each surface.

7.8.6 Data Requirements

The following data shall be reported:

A. Complete description of collector and method of

mounting onto the test bed.

B. The test apparatus used (Method 1 or 2).

C. The type of test performed (Case 1 or 2).

D. The leakage rate (initial and at the end of each

1/3 Rm load cycle)

.

E. A description of any physical damage or distortions

observed during and after the tests.

F. The applied load at which physical damage, distortion

or other structural problems occurred.

33
7.9 Longitudinal Loads

7.9.1 Purpose

The purpose of this test is to determine the ability of the collector mountings* to withstand cyclic loads in the plane of the

longitudinal axis of the collector.

7.9.2 Significance and Use

This test is intended to determine the ability of the mounting for

a rigid, flat plate collector to withstand the cyclic loads such

as are induced by the vibration of the collector from wind gusts

or of the structure on which the collector is mounted.

The load to be imposed by this procedure is intended to simulate

the inertial loads of a filled collector on its mountings when

installed vertically or at an angle.

This test is primarily intended to be performed on innovative

mounting designs which are not conducive to engineering analysis.

It is not intended as a routine test to be performed on all

collector mountings or on all mounting designs.

This test is developmental in nature and is not intended for use

in other than exploratory testing at this time.

7.9.3 Test Specimen

The test specimen shall consist of a complete collector panel and

any mounting brackets or fixtures normally supplied with it or specified by the manufacturer. The specimen shall be mounted in

the test apparatus in accordance with the manufacturer's normal

mounting instructions. All collectors shall be sealed and

capped. Liquid collectors shall be completely filled with tap

water

.

Note: Bleeder valves or petcocks should be provided at the highest

point in the system to permit venting of all air during the filling

operation.

*The hardware used to attach or connect the collector to its support structure.
7.9.4 Apparatus

This test may be performed using either one of the two methods

discussed below. When tested by Method 1, the collector is tested

horizontally with the apparatus illustrated in Figure 6. When

tested by Method 2, the collector is tested vertically with the

apparatus illustrated in Figure 7. The loads are to be applied

through a distribution pad to the geometric center of the collector

side which has been designated by the manufacturer to be uppermost

when installed. The distribution pad shall be designed to provide

an essentially uniform load over a minimum area of 50% of the

loaded side. The line of action for the load shall be parallel to

the absorber plate and perpendicular to the loaded side. The loading

equipment shall be capable of applying loads with an accuracy of 1%.

Method 1 : The test apparatus shall consist of a hydraulic jack or other equivalent means for maintaining a pre-load and imposing an additional load on the collector. The pre-load force shall be

equal to the maximum filled weight of the collector. The imposed

additional load shall be equal to 50% of the maximum filled weight

of the collector. The pre-load shall be maintained on the specimen

for the duration of the test.

Method 2 : The test apparatus shall consist of weights or other

equivalent loading methods that will apply a load parallel to the

long axis of the test specimen. Provisions shall be made to remove

the load as quickly as possible.

7.9.5 Procedure

7. 9. 5.1 Method 1 (Horizontal Test)

STEP 1 - Mount the collector parallel to the test bed as illustrated by Figure 6.

STEP 2 - Attach the loading device so that the load will be imposed

parallel to the test bed and through the geometric center of the

collector. Apply the pre-load force.

STEP 3 - Increase the load to 150% of the maximum filled collector

weight at a rate faster than 25% of filled weight per second and

hold for two (2) minutes.

STEP 4 - Reduce the load to the pre-load value as quickly as possible.

35
t

d>c U -H

•H PI U

-P P .

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Cm

36
FIGURE 7- METHOD 2 - APPARATUS FOR VERTICAL LOAD TEST

37
STEP 5 - Repeat Steps 3 and 4 for a total of fifty (50) cycles.

STEP 6 - Inspect the collector and mountings for physical damage

or distortion.

7. 9. 5. 2 Method 2 (Vertical Test)

STEP 1 - Mount the collector parallel to a flat, rigid, vertical

test frame such as the wall illustrated in Figure 7.

STEP 2 - Attach the loading device or apply weights in such a manner that a load will be imposed parallel to the test bed and

through the geometric center of the collector.

STEP 3 - Apply the load to 50% of the maximum filled collector

weight at a rate faster than 25% of filled weight per second and

hold for two (2) minutes.

STEP 4 - Remove load as quickly as possible.

STEP 5 - Repeat Steps 4 and 5 for a total of fifty (50) cycles.

STEP 6 - Inspect the collector and mountings for physical damage

or distortion.

7.9.6 Data Requirements

Document applied loads and any physical structural damage,

distortion or other degradation resulting from this test.

38
o

FIGURE 7 METHOD 2 - APPARATUS FOR VERTICAL LOAD TEST

37
STEP 5 - Repeat Steps 3 and 4 for a total of fifty (50) cycles.

STEP 6 - Inspect the collector and mountings for physical damage

or distortion.

7. 9. 5.

Method 2 (Vertical Test)

STEP 1 - Mount the collector parallel to a flat, rigid, vertical

test frame such as the wall illustrated in Figure 7.

STEP 2 - Attach the loading device or apply weights in such a manner that a load will be imposed parallel to the test bed and

through the geometric center of the collector.

STEP 3 - Apply the load to 50% of the maximum filled collector

weight at a rate faster than 25% of filled weight per second and

hold for two (2) minutes.

STEP 4 - Remove load as quickly as possible.

STEP 5 - Repeat Steps 4 and 5 for a total of fifty (50) cycles.

STEP 6 - Inspect the collector and mountings for physical damage

or distortion.

7.9.6 Data Requirements

Document applied loads and any physical structural damage,

distortion or other degradation resulting from this test.

38
7.10 Hail Loads

7.10.1

7.10.2

7.10.3

7.10.4

Purpose

The purpose of this test is to determine the ability of flat

plate collector cover plate (glazing) to withstand impact forces

from hailstones or similar flying objects.

Significance and Use

This test is intended to determine the ability of cover plates on flat plate collectors to withstand the impact forces of hailstones in various regions of the United States.

The maximum impact force to be imposed by this test shall be based

on the manufacturer's stated regional limitation on the use of

his collector. In the absence of such a regional limitation, the

maximum impact force to be imposed shall be equivalent to that of

a 1 1/2 in. hailstone falling at its resultant velocity (hailstone

weighing 0.058 lb falling at 112 ft/sec). The maximum impact force

to be imposed, when the manufacturer's regional limitation is

stated, shall be based upon the maximum size of hail to be expected

in the stated regions (See Reference [1], Section S-601-7 and

Figure S-601-7; see also Appendix A-10) of the report.

This test is based on a procedure used by several laboratories in

evaluating roofing and siding materials, but is not an established

standard method. The test does not consider enviromental effects

on materials properties, e.g. ultraviolet and thermal degradation.

Therefore, this test should be considered developmental in

nature.

Test Specimen

The test specimen shall consist of a complete collector panel and

any mounting brackets or fixtures normally supplied with or specified by the manufacturer. The specimen shall be supported

by and parallel to a rigid test frame by the mounting brackets

or fixtures supplied with the collector or specified by the

manufacturer.

Apparatus

The apparatus shall consist of the following:

A. A mechanism (hail gun) capable of propelling 1/2, 3/4, 1 and

1 1/2 inch diameter hailstones at their required velocities

and also capable of being aimed so that the hail will strike

the collector at the specified points (See Figure 8)

.

39
B. An instrument for measuring the hailstone velocities, to an accuracy of +2%, just prior to striking the collector.

C. Molds for forming round ice balls (hailstones) of 1/2, 3/4,

1 and 1 1/2 inch diameter.

D. A freezer controlled at -10+10°F for storage of the ice balls.

E. A rigid test frame for support of the collector during the

test

7.10.5 Procedure

The test procedure consists of impacting the cover plate one time

at each of the four specified points (Figure 8) with successively

larger size hailstones or until some type of failure occurs. Failure is defined as fracture, cracking, tearing, puncture or permanent deformation sufficient to cause malfunction of the cover

plate

The impacts shall be as indicated in the following table within

+ 2 %.

Diameter

of Hail

(in)

, Weight

of Hail

(lb)

Velocity

at Impact

(ft/sec)

1/2 0.002 83

3/4 0.007 91

1 0.017 98

1 1/2 0.058 112

STEP 1 - Mount the collector to the test frame and position the

hail gun so that the path of the ejected hailstones will be

essentially perpendicular (90°+5°) to the plane of the cover plate

STEP 2 - Impact the cover plate at each of the four specified

points (Figure 8) with one of the specified hailstones starting

with the 1/2 inch diameter and consecutively increasing the size

until all four points have been impacted, or until failure occurs.

STEP 3 - Measure the depth of any permanent deformation, describe

other types of failure or deformation observed and note the impact

at which they occur.

7.10.6 Data Requirements

Document any type of failure resulting from this test and the impact

at which it occurred.

40
Impact points shall be within +1 inch of indicated point

FIGURE 8 . IMPACT POINT LOCATIONS

41
7 . 11 Air Collector Rupture and Collapse

7.11.1 Purpose

The purpose of these tests is to determine the ability of air solar

collectors to meet the pressure requirements established by

Underwriters Laboratories [10] for the air duct systems into which

they will be integrated.

7.11.2 Significanc e and Use

These tests are based on the requirements established for the rupture

and collapse of air duct systems by Underwriters Laboratories [10] . These requirements for air duct systems have been incorporated into

the building codes used by many jurisdictions. Since air collectors

are generally incorporated directly into a building air duct system

they can usually be considered as an extension of that air duct

system. The positive pressure (rupture) test is intended to be run

on those collectors which are recommended by the manufacturer for use with positive pressures. Similarly, the negative pressure

(collapse) test is intended to be run on those collectors which are recommended by the manufacturer for operation with negative pressures.

Negative pressure should be used if not specified.

7.11.3 Test Specimen

The test specimen shall consist of a complete solar collector panel

assembly

.

7.11.4 Apparatus

The apparatus shall consist of a pressure source, a means to

regulate and control the pressure and a means to measure the

pressure. The sources of positive pressure (for the rupture test)

and of negative pressure (for the collapse test) shall be capable

of providing positive and negative pressures of at least 2 1/2

times the manufacturer's rated positive and/or negative pressures,

but not less than 1 1/4 inch water column. The inlet and outlet

to the collector are to be sealed airtight by any means consistent

with the use of the material under test. A pressure tap consisting

of pipe or tubing is to be sealed into one end of the test sample

and connected to a water manometer or equivalent pressure gauge

which can be read directly to 0.05 inch water column. An air

supply tap consisting of pipe or tubing is to be sealed into the same or other end of the sample and connected to a source capable

of maintaining the specified positive or negative air pressure.

The collector shall be maintained at ambient temperature throughout

the test.

42
7.11.5 Procedure

7.11.6

STEP 1 - Check the pressure gauge or manometer for zero reading.

STEP 2 - Set the pressure regulator to ambient pressure.

STEP 3 - Attach the air supply to the inlet port of the collector.

STEP 4 - Apply a regulated pressure of 2 1/2 times the manufacturer's

rated positive (rupture) or negative (collapse) pressure, but not

less than 1 1/4 inch water column and maintain this test pressure

for a period of one (1) hour.

STEP 5 - Inspect the collector and document any evidence of damage.

STEP 6 - Allow the specimen to return to ambient pressure.

STEP 7 - Check the pressure gauge or manometer for zero reading.

Data Requirements

Documentation of applied pressure, structural damage (e.g. breaks,

tears, rips, openings, joint movement), evidence of excessive air

leakage and dimensional changes, if any.

43
7.12 Static Pressure Leakage Test

7.12.1

7.12.2

7.12.3

7.12.4

Purpose

The purposes of these tests are to determine the leakage rate of

air collectors, to detect leaks in liquid collectors and to indicate

collector damage induced by other tests included in this report.

Significance and Use

The static pressure leakage test for air solar collectors parallels

a requirement for air ducts established by Underwriters Laboratories

[10]. The same basic test procedure can be used to determine the

leakage in air collectors under both positive and negative

pressure. Air collectors intended for operation under negative

pressure shall be tested under negative pressure. Air collectors

intended for operation under positive pressure shall be tested

under positive pressure. Collectors shall be tested under negative

pressure conditions when the manufacturer does not specify the

conditions under which the collector should be used. The static

pressure leakage tests for liquid solar collectors are based upon

the hydrostatic and pneumatic tests established by the ASME Boiler

and Pressure Vessel Code [11] for the routine testing of pressure

vessels. The testing conditions are based on the maximum allowable

working pressure which can be determined either by engineering

analysis or by testing in accordance with the procedures established

by the ASME code.

Test Specimen

The test specimen shall consist of a complete solar collector panel

assembly

.

Apparatus

The basic apparatus consists of pressure sources (either hydrostatic

and pneumatic or pneumatic for liquid filled collectors; and pneumatic for air collectors) , the necessary regulators to maintain the

specified static pressure and appropriate gauges to indicate both

pressure levels and leakage. Stable temperature conditions shall

be maintained throughout the test to within +5°F of the initial

ambient conditions.

44
7.12.4.1 Air Collector Apparatus

The inlet and outlet of the air collector are to be sealed airtight

by any means consistent with the use of the material under test.

A pressure tap consisting of pipe or tubing is to be sealed into

one end of the test specimen and connected to a water manometer

which can be read directly to 0.01 inch water column or to a pressure gauge of equivalent accuracy. An air tap consisting of

pipe or tubing is to be sealed into the same or other end of the

sample and connected to a source of positive air pressure (for

collectors intended for operation with positive air pressure) or

a means of creating and maintaining negative pressure (for

collectors intended for operation with negative air pressure) . An

air volume meter accurate to within +0.50 cubic foot under the

conditions of the test shall be placed in the air supply system

between the supply source and the test sample. The meter is to

indicate the total volume of air supplied to (positive pressure

operation) or removed from (negative pressure operation) the

sample over the period of the test.

7.12.4.2 Liquid Collector Apparatus

7.12.4.2.1 Overpressure Test

A pressure tap shall be installed in the collector outlet port

which shall be sealed and capped. The collector inlet port shall

be connected to either a hydrostatic source capable of providing

and maintaining a hydrostatic test pressure of 1 1/2 times the

manufacturer's specified maximum allowable working pressure or a pneumatic pressure source capable of providing and maintaining a pneumatic test pressure of 1 1/4 times the manufacturer's specified

maximum allowable working pressure. When the hydrostatic apparatus

is used, a small liquid safety relief valve set to 1 1/3 times the

test pressure is recommended for the pressure test system, in case

a vessel while under test is accidentally overpressurized (e.g. by

overheating) with personnel absent. Indicating pressure gauges

used in testing shall preferably have dials graduated over a range

of about double the intended maximum test pressure but in no case shall the range be less than 1 1/2 times that pressure . The pressure

gauges shall be accurate to within 0.5% of the full scale reading.

45
7.12.4.2.2 Leak Test

The apparatus shall consist of a pneumatic pressure source capable

of applying a pressure equal to the manufacturer's maximum recommended working pressure, a valve capable of isolating the collector

from the pressure source once it has been pressurized and a pressure

gauge meeting the accuracy requirements specified in 7.12.4.2.1

which shall be used to detect pressure drops, if any.

7.12.5 Procedure

7.12.5.1 Air Collector Leak Test

STEP 1 - Check the pressure gauge or manometer for zero reading.

STEP 2 - Set the pressure regulator to ambient pressure.

STEP 3 - Attach the air supply to the inlet port of the collector.

STEP 4 - Apply 0.50 inch water column regulated positive pressure

(for collectors operating under positive pressures) or 0.50 inch

water column regulated negative pressure (for collectors operating

under negative pressures) for one hour.

STEP 5 - Document the volume of air added (positive pressure) or removed (negative pressure) in order to maintain the required

pressure during the period of the test.

STEP 6 - Allow the pressure to equalize to ambient.

STEP 7 - Check the pressure gauge or manometer for zero reading.

7.12.5.2 Liquid Collector Overpressure and Leak Test

STEP 1 - Check the pressure gauge for zero reading.

STEP 2 - Set the pressure regulator to ambient pressure.

STEP 3 - Attach the air supply of hydrostatic pressure source to

the inlet port of the collector.

STEP 4 (Over Pressure Test) - Apply either a hydrostatic pressure

equal to 1 1/2 times the manufacturer's specified maximum allowable

working pressure (after pre-filling the collector with water) or a pneumatic air pressure equal to 1 1/4 times the manufacturer's

specified maximum allowable working pressure. If the pneumatic

pressure test is used, the pressure shall be gradually increased

to not more than 1/2 of the required test pressure and then

increased in steps of approximately 1/10 of the test pressure

until the required test pressure has been reached.

STEP 5 - Allow the collector to equalize to ambient pressure. Then

blow out all liquid from the collector if the hydrostatic test was

used.

46
7.12.6

STEP 6 (Leak Test) - Apply a pneumatic (air) pressure equal to the

manufacturer's specified maximum allowable working pressure;

isolate the test specimen from the pressure source and record any

changes in the reading of the pressure gauge that occur over a period of 15 minutes.

STEP 7 - Allow the pressure to equalize to ambient.

STEP 8 - Check the pressure gauge for zero reading.

Data Requirements

Documentation of the following:

Air Collectors - Applied pressure, calculated volume within the

test specimen based on inside dimensions, total volume of air

recorded by the air meter.

Liquid Collectors - Applied pressure and, if pressure drop is

observed, the rate of pressure drop.

47
7.13 Fire Test

7.13.1

7.13.2

7.13.3

7.13.4

Purpose

The purpose of these tests is to determine the relative fire

hazards created by roof-mounted , flat plate solar collectors

exposed to an external fire source.

Significance and Use

This testing procedure is based on ASTM Standard E108 [12] which

is used to determine the fire-retardant characteristics of roof

coverings that are exposed to a fire originating outside the

building on which they are installed. Provisions based on this

ASTM procedure have been incorporated into the building codes used

in many jurisdictions. Roof mounted solar collectors may have a significant effect on the fire retardant properties of such roof

coverings. This testing procedure is intended for use in the DoE

collector testing program (1) to determine the influence of roof

mounted solar collectors on roof coverings, (2) to determine

modifications in the basic testing procedure that may be required

to make it applicable to solar collectors, and (3) to determine the

effects on roofing of various generic types of collectors. As

written, it is intended for use as a baseline testing procedure.

Variations in test specimen configuration and in test conditions

will be made during the course of the DoE collector testing program

in order to determine the testing procedures that best characterize

the hazard. At the present time, this testing procedure is primarily intended for use in exploratory testing.

Test Specimen

The test specimen shall consist of a complete collector panel

assembly and any mounting brackets or fixtures normally supplied

or specified by the manufacturer.

Apparatus

The test apparatus shall consist of that required in ASTM Standard

E108 to perform the following tests:

A. Intermittent flame exposure

B. Spread of flame

C. Burning brand

48
7.13.5

7.13.6

7.13.6.

7.13.6.

Collector which, according to the manufacturer, may possibly be

installed as an integral part of the roof assembly shall be mounted

on the specified frame work with asbestos cement board to simulate

eaves and cornices. Collectors which, according to the manufacturer,

cannot be mounted as an integral part of the roof assembly shall be

mounted on a roof deck section covered with a Class C covering

material. Angles for the collector, roof deck and the stand-off

distance shall be specified for the test. In either case the

mounting procedure used shall be based on the manufacturer's

recommended mounting practice. In any case where a single collector

is not of adequate size to meet minimum test requirements, two or more panels may be connected as recommended bv the manufacturer. All

collectors shall be tested dry, i.e. without heat transfer fluid.

Procedure

One collector assembly shall be subjected to each of the following

ASTM Standard E108 tests:

A. Intermittent flame exposure

B. Spread of flame

C. Burning brand

STEP 1 - Assure collector is dry (contains no heat transfer fluid)

.

STEP 2 - Prepare test set-up in accordance with Reference [12].

STEP 3 - Conduct required tests in accordance with Reference [12].

Data Requirements

1 Description of test specimen and mounting procedure.

2 Document data concerning both the collector assembly and roof

covering materials for each of the tests in accordance with

Reference [12].

49
8.0 REFERENCES

[ 1]

[ 2 ]

t 3]

[ 4]

[ 5]

[ 6]

[ 7]

[ 8 ]

INTERMEDIATE MINIMUM PROPERTY STANDARDS SUPPLEMENT, SOLAR HEATING

AND DOMESTIC HOT WATER SYSTEMS, 1977 Edition, HUD 4930.2,

Prepared for HUD by NBS , Available from Government Printing

Office, SD Catalog No. 0-236-648, Price $12.00.

INTERIM PERFORMANCE CRITERIA FOR SOLAR HEATING AND COOLING SYSTEMS

IN COMMERCIAL BUILDINGS, November 1976, NBS Report NBSIR 76-1187,

Prepared for ERDA by NBS, Available from NTIS, Order No.

PB 262-114, Price $5.50.

INTERIM PERFORMANCE CRITERIA FOR SOLAR HEATING AND COMBINED HEATING/

COOLING SYSTEMS AND DWELLINGS, January 1975, Prepared for HUD

by NBS, Available from Government Printing Office, SD Catalog

No. 0324-01043, Price $1.90.

METHODS OF TESTING TO DETERMINE THE THERMAL PERFORMANCE OF SOLAR

COLLECTORS, February 1977, ASHRAE Standard 93-77, Available

from American Society of Heating, Refrigerating and Air

Conditioning Engineers, Inc., Publications Sales Department,

345 E. 47th Street, New York, N.Y. 10017.

SURFACE BURNING CHARACTERISTICS OF BUILDING MATERIALS, ASTM Standard

No. E-84-76a, Available from American Society for Testing and

Materials, 1916 Race Street, Philadelphia, PA 19103.

WATER PENETRATION OF EXTERIOR WINDOWS, CURTAIN WALLS, AND DOORS BY

UNIFORM STATIC AIR PRESSURE DIFFERENCE, ASTM Standard No.

E-331-70 (Reapproved 1975), Available from American Society

for Testing and Materials, 1916 Race Street, Philadelphia, PA

19103.

REFRIGERATION AND AIR CONDITIONING CONDENSING AND COMPRESSOR UNITS,

UL Standard No. 303, August 12, 1974, Available from Underwriters Laboratories, Inc., 207 East Ohio Street, Chicago, IL

60611.

BUILDING CODE REQUIREMENTS FOR MINIMUM DESIGN LOADS IN BUILDINGS

AND OTHER STRUCTURES, ANSI A58 . 1 - 1972, Available from

American National Standards Insitute, 1430 Broadway, New York,

N.Y. 10018.

50
[ 9 ]

[10]

[ 11 ]

[ 12 ]

CONDUCTING STRENGTH TESTS OF PANELS FOR BUILDING CONSTRUCTION,

ASTM E72-74a, Available from American Society for Testing and

Materials, 1916 Race Street, Philadelphia, PA 19103.

FACTORY-MADE AIR DUCT MATERIALS AND AIR DUCT CONTAINERS, UL Standard

No. 181, April 30, 1974, Available from Underwriters

Laboratories, Inc., 207 East Ohio Street, Chicago, IL 60611.

ASME BOILER AND PRESSURE VESSEL CODE, ANSI/ASME BPV-VIII-1,

Section VIII, Division 1, UG-98, 99 and 100, 1977 Edition,

Available from the American Society of Mechanical Engineers,

United Engineering Center, 345 East 47th Street, New York,

N.Y. 10017.

FIRE TESTS OF ROOF COVERINGS, ASTM Standard No. E-108-75, Available

from American Society for Testing and Materials, 1916 Race

Street, Philadelphia, PA 19103.

51
.

'

.

.
APPENDIX A

PROPOSED RATING CRITERIA

FOR FLAT PLATE SOLAR COLLECTORS

A-l Thermal Performance (Paragraph 7.1)

The thermal performance of flat plate solar collectors shall be

determined and reported in accordance with ASHRAE Standard 93-77

[4], and Appendix B of this document. Measurements made after the

30-day no-flow degradation test shall be used to determine

performance

.

A-2 30-Day No-Flow Degradation (Paragraph 7.2)

Collectors shall not exhibit a change in the product of F (xa) K 0

(intercept) or FDUT (slope) that would result in a 10% or greater K Li decrease in thermal efficiency for the proposed application.

Values of AT/I typical of the application under consideration

(such as approximately 0.04 for domestic hot water, 0.08 for space

heating and 0.11 for space cooling) should be used to determine

the point on the efficiency curve that should be used to obtain

the change in efficiency. In addition, the criteria in A-3 and

A-4 shall be met during the 30-day no-flow test sequence.

A-3 Thermal Shock/Water Spray Test (Paragraph 7.3)

The collector shall not exhibit either of the following:

A. Visual observation of catastrophic or structural failure.*

B. Visual evidence of leakage for collectors designed to be

waterproof

.

A-4 Thermal Shock/Cold Fill Test (Paragraph 7.4)

The collector shall not exhibit either of the following:

A. Visual observation of catastrophic or structural failure.

B. Evidence of leakage rate greater than that allowed in

Paragraph A-12.

A-5 Rain Test (Paragraph 7.5)

The collector shall not exhibit either of the following:

A. Visual observation of water penetration within the collector.

B. An increase in the weight of the collector by 1% or more.

*Failure that would not permit a collector to perform its intended function

or that would result in the creation of a hazard.

A-l
A

Thermal Cycling Test (Paragraph 7.6)

The collector shall not exhibit either of the following:

A. Visual observation of catastrophic or structural failure.

B. Evidence of leakage rate greater than that allowed in

Paragraph A-12.

A-7/A-8 Positive, Negative and Combined Loads (Paragraphs 7.7 and 7.8)

The procedures outlined below shall be followed to determine the

design load ratings, U, assigned to a collector for positive live

loads and for negative and combination wind loads. (The values

of U required for a specific application can be determined in

accordance with [8] by the system designer.)

The average maximum load (R ) resisted by a collector sample during

these tests should exceed the design load rating (U) by a factor

which is a function of the number of specimens in the sample and

of the variability in the materials used.

The design load rating (U) can be determined from the test results

using the following relationship:

U = R ( 1-a v

)

m

where: Rm

= the mean resistance, is the average maximum load

resisted by the collector sample as determined

by testing.

a = a factor dependent on the number of specimens

(n) tested by a specific test method,

v = coefficient of variation.

The factor a for 95 percent confidence limits may be taken from

the following table:

n

1

2

3

4

5 10

The factor v may be taken from the

tests. If variability data is not

for v should be used.

a 3.29

2.81

2.59

2.47

2.38

2.17

literature or from auxiliary

available a conservative estimate

AA9

A- 10

A- 11

A- 12

If only one test specimen is used per test method and if v is equal

to 0.2 (this coefficient is given in the literature for glass), then

U = 0.34 Rm

The value of v given above for glass shall be used in the absence

of variability data for other materials that would affect the

collector strength. However, the value of U obtained with this

value of v may be somewhat conservative for some materials.

Similarly, if failures do not occur during the testing, the values

of U calculated with the maximum test loads specified in this report

will be conservative.

Longitudinal Load Test (Paragraph 7.9)

The collector or its mounting shall not exhibit visual evidence of

physical damage or permanent distortion.

Hail Loads (paragraph 7.10)

Collectors which are not damaged by the impact of 1 1/2 inch

diameter hailstones will have a high probability of withstanding

hailstorms in most regions of the United States without damage.

The mean annual days with hail for various regions of the United

States are indicated in Figure S-601-7 of Reference [1] . The

impact from the 1 inch hailstones will apply to regions with up to

4 mean annual days with hail, the 3/4 inch hailstones to regions

with up to 2 days and the 1/2 inch hailstones to regions with less

than 1 day with hail per year.

Air Collector Rupture and Collapse (Paragraph 7.11)

The collector shall not exhibit visual evidence of catastropic or structural failure including rupture by breaks, tears, rips or other openings.

Static Pressure Leakage Test (Paragraph 7.12)

Air Collectors - The total volume of air recorded by the air meter

from the time beginning with the establishment of the test pressure,

to the end of the test period (one hour) , is not to exceed 20

multiplied by the volume of the collector panel assembly [10].

Liquid Collectors - A pressure drop or visual evidence of leakage

shall not occur.

A3
A- 13 Fire Tests (Paragraph 7.13)

A- 13.1 General

The collector shall not reduce the fire resistance of a Class C

[12] roof assembly. The collector shall be effective against light

fire exposure. It shall not be readily flammable, shall afford a measurable degree of fire protection, and shall not slip from

position or present a flying brand hazard. The intent is to

indicate fire-resistance characteristics against fire originating

from sources outside the building and should not be construed as having any significance with respect for suitability for use after

fire exposure.

A- 1 3 . 2 Rating Criteria

A- 13 .2.1 The collector must meet the requirements for a Class C rating given

in Reference [12] for the intermittent flame, spread of flame and

burning brand tests with the exception that only one series of tests

shall be performed.

A. At no time during or after the intermittent flame, spread

of flame, or burning brand tests (1) shall any portion of

the collector be blown or fall off the test deck in the form

of flaming or glowing brands that continue to glow after

reaching the floor or (2) shall the roof deck be exposed or portions of the roof deck fall away in the form of particles

that continue to glow after reaching the floor.

B. At no time during the intermittent-flame tests shall there

be sustained flaming of the underside of the deck.

C. In the burning brand tests there may be sustained flaming

on the underside of the deck of not more than 20% of the

brands applied.

D. At the conclusion of the spread of flame tests, the flaming

shall not have spread beyond 13 ft (the top of the deck)

.

There shall have been no significant lateral spread of

flame from the path directly exposed to the test flame.

A-13.2.2 The flame spread classification index, as measured by ASTM

Standard E-84 [5] for all insulation materials shall not exceed

the following values:

Plastic Foam 75

Other Insulation Material 150

A4
A-13.2.3 Materials used as duct liners shall comply with the requirements

of Paragraph 5.3 of Reference [10] for Class 1 air ducts.

APPENDIX B

CALCULATION OF ALL-DAY SOLAR COLLECTOR EFFICIENCY

The series of solar collector tests conducted according to ASHRAE

Standard 93-77 results in a determination of the thermal efficiency of the

collector at "near-normal-incidence" conditions as a function of the

difference between the inlet fluid temperature to the collector and the

ambient temperature as well as the incident solar radiation normal to the

collector plane. In addition, the parameter "incident angle modifier" is

determined which allows one to predict how the thermal efficiency changes

as the angle between the direct solar beam and the outward drawn normal

to the collector plane increases. From these two performance factors, it

is possible to predict the "all-day" collector efficiency. In order to

complete the calculation for a given day, it is necessary to know the

following as a function of time throughout the day:

1. inlet fluid temperature to the collector, t- . ,

2. ambient temperature, t^

3. incident solar radiation in the plane of the collector, I T ,

4. collector F (xa) n and incident angle modifier.

The calculation procedure is carried out in a series of steps indicated in

the following table.

Measurements made after the 30-day no-flow degradation test shall be used to

determine performance.

B-l
TABLE B-l. TYPICAL COMPUTATION OF ALL DAY SOLAR COLLECTOR EFFICIENCY

CALCULATION STEPS

HOUR OF THE DAY , SOLAR TIME DAILY

6-7 7-8 8-9 9-10 10-11 11-12 12-1 1-2 2-3 3-4 4-5 5-6 TOTAL

1. Inlet fluid temp to

collector, t- . , °C 49 49 49 49 50 50 51 52 54 54 54 54

2. Ambient air temp, V

° c 10 10 10 13 15 16 16 22 24 24 18 18

3. Incident radiation

on collector plane,

I T , W/m2

, (Table A2

,

ASHRAE 93-77) 90 186 454 693 876 993 1031 993 876 693 454 186 7525

4. Collector thermal

efficiency at normal

incidence, determined

in accordance with

Sections 8.3.2 and

8.5 of ASHRAE 93-77

and using data from

lines 1, 2, and 3. . 02 .15 .38 .42 . 46 .46 .46 .43 .42 .18 .02

5. Incident angle

between the direct

solar beam and outward drawn normal

to the collector

plane, 9 90 75 60 45 30 15 15 30 45 60 75 90

6. Incident angle modifier, determined in

accordance with

Sections 8.3.3 and

8.6 of ASHRAE 93-77

and using the value

of 9 from line 5. .48 .82 .93 .97 1.0 1.0 .97 .93 . 82 .48

7. Energy output from

the collector, W/m2

, (line 3)x(line 4+

[Fr{

t

a

}

e f n ] x [{line 6 } — 1 ]

)

0 0 229 350 457 474 437 333 180 0 2460

8. Collector thermal

efficiency, line 7/

line 3 .33

B-2
APPENDIX C

THE DOE COLLECTOR TESTING PROGRAM*

TO: Interested Solar Collector Manufacturers

Interim Collector Thermal Performance Testing Program

The Department of Energy invites solar collector manufacturers to participate

in a Federally-sponsored collector testing program. This program is part of

a joint Government/industry effort to accelerate the development and implementation of a certification, rating and labeling program for solar collectors.

The Solar Energy Research and Education Foundation (SEREF) , under contract to

DoE, is developing procedures for certifying, rating and labeling solar

collectors

The DoE is sponsoring the testing of solar collectors. The test data will be

used by SEREF to produce a catalog of collector ratings. It is expected that

this program will stimulate the implementation of an ongoing industry certification program.

This program will also insure the identification of reli-able, durable solar

equipment for the consumer and is responsive to the tax credit provisions of

the proposed National Energy Act.

Tests will include the thermal performance of solar collectors in accord with

ASHRAE Standard 93-77, a 30 day stagnation test, fire resistance, structural

and environmental tests in accord with NBSIR 77-1305. The ASHRAE test is a consensus standard, data from which can form the basis for a rating, labeling,

and certification program. All collectors in the program will be tested per

the ASHRAE test and the 30 day stagnation test. The other tests documented

in NBSIR 77-1305 are considered to be tentative and in need of confirmation

or modification, therefore data will be gathered from collectors considered

representative of a sufficiently large class. These data will help develop

the appropriate test procedures and requirements for future consensus

standards. Thermal and stagnation tests will be duplicated in some cases to

determine whether climatic variation affects the test results

*The above material was included in a notice sent by DoE to solar collector

manufacturers

C—
NBS-1 14A (REV. 7-73)

U.S. DEPT. OF COMM. 1 . PUB LIC ATION OR R E PORT NO. 2. Gov’t Accession

BIBL-'OCR^PHIC DATA

NBSIR 78-1305A

N °'

3. Recipient’s Accession No.

4. TITLE AND SUBTITLE

Provisional Flat Plate Solar Collector Testing Procedures:

First Revision

5. Publication Date June 1978

6. Performing Organization Code

744

7. AUTHOR(S)

n. WakRTTiary F.. R. Streed. T. W. Reichard. L. E. Cattaneo

8. Performing Organ. Report No.

9. PERFORMING ORGANIZATION NAME AND ADDRESS

NATIONAL BUREAU OF STANDARDS

DEPARTMENT OF COMMERCE

WASHINGTON, D.C. 20234

10. Project/Task/Work Unit No. 7446505 (Task 4)

11. Contract/Grant No. EA-77-A-01-6010

12. Sponsoring Organization Name and Complete Address (Street, City, State, ZIP)

Department of Energy

Office of Conservation and Solar Applications

20 Massachusetts Avenue, NW

Washington, DC 20545

13. Type of Report & Period Covered

Interim

14. Sponsoring Agency Code

15. SUPPLEMENTARY NOTES

This report is the first revision to NBSIR 77-1305, "Provisional Flat Plate Solar

Collector Testing Procedures."

16. ABSTRACT (A 200-word or less factual summary of most significant information. If document includes a significant

bibliography or literature survey, mention it here.) This document represents the first revision to NBSIR 77-1305* The test methods contained in this report and the provisional rating criteria presented in an appendix

are intended for use in determining the thermal performance, and to aid in the

assessment of the safety and durability/reliability of flat plate solar collectors.

These test methods and rating criteria have been selected after the review of over

400 accepted industry standards and are consistent with the intent of the U.S.

Department of Housing and Urban Development (HUD) Minimum Property Standards (MPS)

and the Interim Performance Criteria (IPC) prepared by the National Bureau of

Standards (NBS) for the Department of Energy (DoE) and HUD respectively. Many of the

test methods and rating criteria contained in this report are preliminary in nature

and will be evaluated during a collector testing program being sponsored by DoE. It

is, therefore, reconmended that regulatory agencies consider the developmental status

of these procedures in evaluating their suitability for adoption. It is intended that

revisions will be made as more experience is gained and inputs received from appropriate industry representatives, testing laboratories, designers, etc.

17. KEY WORDS (six to twelve entries; alphabetical order; capitalize only the first letter of the first key word unless a proper name; separated by semicolons

)

Durability/reliability; fire safety; rating criteria; solar collectors; structural

performance; testing procedures; thermal performance

18. AVAILABILITY [X] Unlimited

For Official Distribution. Do Not Release to NTIS

| Order F rom Sup. of Doc., U.S. Government Printing Office Washington, D.C. 20402, SD Cat. No. C 1 3

fXl Order From National Technical Information Service (NTIS)

Springfield, Virginia 22151

19. SECURITY CLASS 21. NO. OF PAGES

(THIS REPORT)

65

UNCL ASSIFIED

20. SECURITY CLASS 22. Price (THIS PAGE)

$5.25

UNCLASSIFIED

USCOMM-DC 29042- P 74

ri!I