NBSIR 77-1305

Provisional Flat Plate Solar

Collector Testing Procedures

Center for Building Technology

Institute for Applied Technology

National Bureau of Standards

Washington, D.C. 20234

September 1977

Prepared for Energy Research and Development Administration

Division of Solar Energy

Washington, D.C. 20545
'It

I:
NBSIR 77-1305

PROVISIONAL FLAT PLATE SOLAR

COLLECTOR TESTING PROCEDURES

Center for Building Technology

Institute for Applied Technology

National Bureau of Standards

Washington, D C. 20234

September 1977

Prepared for Energy Research and Development Administration

Division of Solar Energy

Washington, D.C. 20545

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, Acting Director

ACKNOWLEDGMENTS

This document 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 include:

Wyle Laboratories: National Bureau of Standards:

David R. Reese David Waksman

Howard H. Yen Elmer R. Streed

Joe H. Johnson Thomas W. Reichard

Robert E. Losey Edgar V. Leyendecker

Wayne L. Swanson Louis E. Cattaneo

Rick E. Pitman Larry W. Masters

Janet M. Kennedy William D. Walton

1
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

1 in? = 6.45 X 10 ^ meter‘d

1 ft^ = 0.09290 meter^

VOLUME

1 in? = 1.639 X 10 ^ meter^

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

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^ 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^ joule

POWER

1 Watt = lx 10^ erg/second

1 BTU/hr = 0.2931 Watt

TEMPERATURE

t°C = 5/9 (t°F - 32)

HEAT

1 BTU*in./hr *ft^* °F = 1.442 x lO"^ W/m«K

(thermal conductivity)

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

1 langley = 4.184 x lo'^ J/m^ = 1 cal/cm^ = 3.69 BTU/ft^

11
TABLE OF CONTENTS

Page

1 . 0 INTRODUCTION 1

2 . 0 GENERAL 3

2.1 Purpose 3 2.2 Scope 3 2.3 Test and Evaluation Methods 3 2.4 Evaluation Criteria 3

3.0 SELECTION AND CHARACTERIZATION OF TEST SPECIMENS 5

3.1 Criteria 5 3.2 Identification 5 3.3 Materials 5 3.4 Specifications 5 3.5 Drawings/Manuals 6

4.0 RECEIVING INSPECTION 7

4.1 Damage Inspection 7 4.2 Documentation Compliance Inspection 7 4.3 Specimen Rejection 7

5.0 SUGGESTED SEQUENCE OF TESTS 8

6.0 DOCUMENTATION REQUIREMENTS 9

6.1 General 9 6.2 Instrumentation Calibration Records 9

6.3 Test Data 9 6.4 Final Report 10

7.0 TEST METHODS 11

7.1 Thermal Performance Test 11

7.2 No-Flow 30-Day Degradation 12

7.3 Thermal Shock/Water Spray Test 15

7.4 Thermal Shock/Cold Fill 16

7.5 Rain Test 17

7.6 Thermal Cycling 20

7.7 Positive Live Loads 22

7.8 Negative Live Loads 25

7.9 Longitudinal Loads 30

7.10 Hail Loads 34

7.11 Static Over-Pressure Test 37

7.12 Static Pressure Leakage Test 39

7.13 Fire Tests 41

8.0 REFERENCES 43

APPENDIX A - PROPOSED RATING CRITERIA FOR FLAT PLATE

SOLAR COLLECTORS A-1

APPENDIX B - CALCULATION OF ALL-DAY SOLAR COLLECTOR EFFICIENCY B-1

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1.0 INTRODUCTION

This document was prepared by the National Bureau of Standards

with the assistance of Wyle Laboratories. It is intended

for use;

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

Energy Research and Development Administration (ERDA)

.

The information obtained during this ERDA program will

form a data base that can be used by consumers, code

officials, industry representatives and other

concerned parties in determining key parameters that

would affect solar collector performance.

2. As a resource document in the development of collector

testing standards by consensus standards organizations

such as the American Society for Testing and Materials.

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 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 ERDA and

HUD, respectively [2&3] and can be used as an aid in determining

compliance with these documents. These test methods and rating

criteria do not, however, represent a consensus of industry and

are therefore provisional in nature. It is intended that revisions will be made as more experience is gained and inputs

received from appropriate industry representatives, testing

laboratories, designers, etc.

Numbers in brackets throughout this document indicate

references given on Page 43.

1
Comments concerning these tests are invited and should be

addressed to:

Manager, Solar Energy Program

National Bureau of Standards

Building 225, Room A-114

Washington, DC 20234

2
2.0 GENERAL

2.1 Purpose

The purpose of this document is

for determining the performance,

of flat plate solar collectors,

rating criteria utilizing these

to set forth interim test methods

reliability, durability and safety

Provisional recommendations for

tests are presented in Appendix A.

2.2 Scope

The test methods contained herein apply only to 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.

2.3 Test and Evaluation Methods

Test methods contained herein address the following specific areas

a. Thermal Performance

b. Reliability/Durability

c. Safety

2.4 Evaluation Criteria

The evaluation criteria utilized in this document fall into three

distinct categories as follows:

2.4.1 Performance Testing - These tests require the use of a test

facility specifically designed to evaluate solar collectors

in accordance with the requirements set forth in ASHRAE Standard

93-77 [4]

This category includes requirements for no-flow

(stagnation) tests and leakage tests.

3
2.4.2 Physical Properties and Structural Testing - These tests are used

to determine durability, reliability and safety, and require the

services of an environmental test facility.

2.4.3 Engineering Review and Analysis - Requires no test facility.

Specific requirements regarding the materials used and their

properties are contained in the HUD Intermediate MPS (4930.2) [1]

and ERDA and HUD IPC [2,3].

4
3. 0 SELECTION AND CHARACTERIZATION OF TEST SPECIMENS

3 . 1 Criteria

The test specimens should be randomly selected from a normal

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

3 . 2 Identification

Each collector submitted for testing shall have permanently

affixed thereto the following:

3.2.1 Manufacturer's name and address.

3.2.2 Model name and/or number.

3.2.3 A serial number.

3 . 3 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

3.3.1 Optical and other properties per Table 2, ASHRAE Standard

93-77 [4].

3.3.2 Insulation and duct liner flame spread per ASTM Standard

E-84-76a [9].

3 .

Specifications

A document shall be furnished with each test specimen providing the

following information to the extent possible:

3.4.1

3.4.2

3. 4. 2.1

3. 4. 2.

3. 4. 2.

3. 4. 2.

3. 4. 2.

3. 4. 2.

Manufacturer's recommended heat transfer fluid.*

Collector operating parameters.*

Recommended operating flow rate.*

Recommended fill rate.

Recommended maximum operation pressure.*

Maximum* and minimum permissable no-flow temperature limitations.

Normal operating temperature range.*

Limitations

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

5
Mounting and handling instructions.

Structural load limitations.

Drawings/Manuals

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

sufficient detail to accurately depict:

Collector dimensions.*

Cover plate dimensions and mounting details.*

Absorber plate details including:

a. Dimensions

b. Fluid Capacity.

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

6
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 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.

7
5.0 SUGGESTED SEQUENCE OF TESTS

5.1 Where all tests are conducted, the following sequence is suggested.

This sequence requires the use of two collectors for all tests

except those concerned with fire testing for ignition from an external source. Times are approximate and could vary considerably

depending on location of the test facility.

Collector #1 Collector #2

Test Para

.

Days Test Para. Days

Thermal Performance 7.1 5 Rain 7.5 1 No Flow, 30 Day 7.2 50 Static Pressure 7.12 1 (Includes Thermal

Shock/Water Spray

& Thermal Shock/

(7.3 & 7.4)

Leakage

Thermal Cycling*** 7.6 10

Cold Fill Tests) Positive, Negative, 7.7, 7.8,

Thermal Performance

Check* 7.1 5

Longitudinal & Hail

Loads***

7.9 &7.10 5

Fire Test** 7.13 1 Static Over-Pressure 7.11 1 Fire Test 7.13 1

TOTAL 61 TOTAL 19

5.2 Unless otherwise specified herein all tests shall be conducted with

the test specimen mounted in accordance with the manufacturer's

recommendations. In the event that the manufacturer provides

optional mounting, testing will be performed under the configuration considered the most critical by the test engineer. The

rationale for selection shall be included in the test report.

The Thermal Performance Check (ASHRAE Standard 93-77 test after the

30-day cumulative exposure) does not require the 3-day pre-exposure

or remeasurement of the incident angle modifier and time constant.

The check is conducted to demonstrate the magnitude of changes in

the intercept and slope of the efficiency curve. A minimum of

three measurements at operating conditions covering the range of

0.1 to 0.4 hr* °F* ft^/BTU shall be performed.

These tests will probably require more than two collectors. The

actual number is dependent on the size of the collectors.

Includes static pressure leakage testing per 7.12.

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.

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 Niomber and Accuracy of Each Instrument used

to Measure or Record Test Data.

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.

9
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.

10
7.0 TEST METHODS

7 . 1 Thermal Performance Test

Thermal performance testing shall be conducted in accordance

with ASHRAE Standard 93-77. A recommended procedure for

calculating all-day solar collector efficiency is contained

in Appendix B.

11
No-Flow 30-Day Degradation

Purpose

The purpose of this test is to document potential degradations

resulting from prolonged exposure to natural environments.

This method involves the exposure of the collector to solar

radiation at an actual test site and measuring the change

in collector efficiency as a result of the exposure.

Methodology

The parameters F (ra) and F U shall be determined in accordance

K H J_i with the test procedure described in ASHRAE Standard 93-77 both

before and after exposing the collector panel assembly to the

Exposure Test described below.* Both the before and after

collector thermal performance tests (ASHRAE Standard 93-77)

shall be performed utilizing the same test facility under

similar climatic conditions.

Test Specimen

The test specimen shall consist of a complete air or liquid

collector panel assembly.

Pre-Exposure Preparation

Air Collectors shall be sealed and capped with a pressure

relief device set to a value of -0% to +10% of the collector

manufacturer's maximum recommended operating pressure. The

inlet shall be equipped with a check valve and desiccant to

allow the admission of dry air if internal pressures become

negative (less than atmospheric)

.

The Thermal Performance Check (ASHRAE Standard 93-77 test after

the 30-day cumulative exposure) does not require the 3-day

pre-exposure or remeasurement of the incident angle modifier

and time constant. The check is conducted to demonstrate the

magnitude of changes in the intercept and slope of the efficiency

curve (see Paragraph 19, Reference [4]). A minimum of three

measurements of operating conditions [ (t_ . -t )/I] covering the

2

r , 1 a range of 0.1 to 0.4 hr «°F »f t'^/BTU shall be performed.
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 of -0% to +10% of

the manufacturer's recommended maximum operating pressure.

7. 2. 4. 3 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 sealed and the outlet provided

with a pressure relief valve set to a value of -0% to +10%

of the manufacturer's recommended operating pressure.

7.2.5 Exposure Conditions

Exposure conditions shall consist of 30 days of cumulative

exposure to a minimum daily incident solar radiation flux

2 of 1500 BTU/ft -day as measured in the plane of the collector

aperture. The exposure conditions shall include at least

one consecutive four-hour period with a minimum flux of

2 300 BTU/f t *hr** . This exposure must occur after the collectors

have boiled dry where applicable. The average ambient temperature

2 shall be 80°F or higher during the 300 BTU/ft *hr exposure time.

The collector shall be mounted to a rack at a tilt angle such

that the incident solar radiation during solar noon is

within +10° of the normal to the plane of the aperture.

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

instances when they specifically prohibit the use of distilled

water

Collector orientation changes or supplementary reflectors may be

2 necessary to obtain the 300 BTU/ft *hr insolation level at certain

locations

13
7.2.6 Data Requirements

7. 2. 6.1 The exposure conditions including hourly insolation, ambient

temperature and wind velocity and daily precipitation shall be

recorded to enable determination of the average daily values.

Values shall be recorded every 30 minutes during the

2 300 BTU/ft • hr exposure.

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

be plotted on the same graph for comparison purposes.

CommentaryThe purpose of the "no-flow" test is to identify, in a short

period of time, potential problems with collector materials or construction.

The 30 days do not necessarily have to be consecutive but the test should be

performed on a continuous basis until the solar radiation levels have been

achieved for 30 cumulative days. It is recognized that other heat transfer

fluid materials exist which may be preferred by the manufacturer or designer.

If the test is conducted in a manner other than that prescribed, the

collector specification shall state the specific conditions used during the

test and identify the pertinent limitations regarding collector array

installation and operation. The test procedure is based upon draft versions

of a test method in preparation by ASTM and will be superceded by a consensus

test method as soon as it becomes available.

14
7.3 Thermal Shock/Water Spray Test

7.3.1 Purpose

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

collector to withstand thermal shock caused by heavy rains falling

on the heated collectors.

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 one hour

of direct sun (minimum 270 BTU/ft^*hr) and oriented within 10°

of the normal to the sun.

7.3.3 Apparatus

The apparatus consists of 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 not exceed 86 °F during the test.

7.3.4 Procedure

2 STEP 1 - Adjust the water spray to provide 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

7.4.1

7.4.2

7.4.3

7.4.4

7.4.5

**

Thermal Shock/Cold Fill

Purpose

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

collector after being subjected to thermal shock induced through

filling the hot collector with relatively cool heat transfer fluid

during daytime start-up.

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 one hour of direct sun (minimum

2 300 BTU/ft »hr) and oriented within 10° of the normal to the sun.*

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 not exceed 75°F.

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 leakage

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.

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.

2 When the flow rate is not specified, a rate of 1.5 gph/ft for

2 liquid-filled collectors and 2 SCFM/ft 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 winddriven rain.

7.5.2 Test Specimen

The test specimen shall consist of a complete air or liquid

collector panel assembly.

7.5.3 Apparatus

The collector shall be mounted in the apparatus illustrated in

Figure 1 or any arrangement of equipment capable of performing

the test procedure. The water-spray system shall have nozzles

spaced to wet those areas vulnerable to water leakage. For

additional details on construction and calibration of the waterspray system consult ASTM Standard E331 [6]

The test consists

of sealing the solar collector into or against one face of a test chamber, supplying air to or exhausting air from the chamber

at the rate required to maintain the test pressure difference

across the collector, while spraying water onto the face of the

collector at the required rate. The application rate of 3.4 gal.

of water per square foot of effective collector area per hour and

2 an air pressure of 10 Ibf/ft (1.92 in. head of water) above

atmosphere within the chamber is equivalent to 5-1/2 inches of

rain per hour accompanied by a 62.5 mph wind [5].

7.5.4 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 - Adjust the water spray to provide a uniformly

2 distributed spray at the rate of 3.4 gph/ft over the entire

collector top surface.

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

18
2 STEP 4 - Apply an air-pressure difference of 10 Ibf/ft (1.92 in.

head of water)

STEP 5 - Maintain air-pressure difference and water spray for

15 minutes.

STEP 6 - Remove the air-pressure difference and stop the water

spray.

STEP 7 - Dry exterior collector surfaces and weigh the collector.

Observe and record the points of water penetration into the

collector interior.

STEP 8 *- 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

STEP 9 - Repeat Steps 3 through 7 with a water spray and air-pressure

2 2 difference of one-half the values (1.7 gph/ft and 5 Ibf/ft ).

7.5.5 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.

19
7.6 Thermal Cycling

7.6.1 Purpose

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

collector after being subjected to periodic freezing conditions.

7.6.2 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 Collectors shall be sealed and capped with a pressure

relief device set to a value of -0% to +10% of the

collector manufacturer's maximum recommended operating

pressure. The inlet 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 of within -0% to +10% of the

manufacturer's recommended maximum operating pressure.

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.

7.6.3 Apparatus

A temperature chamber capable of cycling the enclosed temperature

region from ambient to -25 °F at a rate of 40 °F to 60 °F per hour.

20
7.6.4 Procedure

STEP 1 - Place the collector in the temperature chamber using

standard installation techniques.

STEP 2 - Lower the internal chamber temperature to -25 °F at a rate of 40 °F to 60 °F per hour and maintain until temperature

sensor reaches -10 °F. Lower test temperatures should be used

when specified by the collector manufacturer.

STEP 3 - Raise the internal chamber temperature to ambient

(~70°F) at a rate of 40°F to 60°F per hour and maintain until

absorber plate temperature reaches ambient temperature.

STEP 4 - Repeat Steps 2 and 3 for a total of ten (10) cycles.

STEP 5 - Static pressure leak test in accordance with

Paragraph 7.12 to verify structural integrity.

7.6.5 Data Requirements

Document any visual evidence of damage and leakage per

Paragraph 7.12.

21
7 . 7 Positive Live Loads

7.7.1 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 and/or

positive wind pressure.

7.7.2 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 Paragraph 7.12.

7.7.3 Apparatus

The collector to be tested shall be mounted in the apparatus

illustrated in Figure 2. The collector shall be supported on the

test bed in accordance with the manufacturer's recommendations.

Connect a reaction platform wider and longer than the specimen and

parallel to the face to be loaded. The reaction platform shall be

supported by use of tie rods. Place an airtight bag (20-mil PVC

plastic film or other pliable material) as wide as the specimen

and as long as the span, 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 +1%

by means of a manometer or other pressure measuring device.

7.7.4 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 Paragraph 7.12.

STEP 3 - Apply a uniform load of 30 psf at the rate of 5 psf per

minute

STEP 4 - Maintain the 30 psf load for a period of ten

minutes and then relieve the applied load.

STEP 5 - Determine the leakage rate in accordance with

Paragraph 7.12.

22
0) w

(0upmp

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-P -H E-i >i W -P W rH

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4J T3 -H >i O X

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X c

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g

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23
STEP 6 Repeat Steps 3, 4 and 5 increasing the applied load in

increments of 20 psf until some type of physical damage is

observed or to a maximum of 150 psf.

7.7.5 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.

24
7.8 Negative Live Loads

7.8.1 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

primarily to the outer surface of the collector which would

create a suction 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 outer surface and uplift on the

inner surface; i.e., when the collector is intended for installation on open racks or on >stand-offs greater than twelve (12)

inches from a surface such as a roof*.

7.8.2 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 Paragraph 7.12.

7.8.3 Apparatus

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

with the manufacturer's instructions and as illustrated in either

Figure 3 or Figure 4. Collectors with rigid flat glazing materials

shall be tested using Method A in the apparatus shown in Figure 3.

Collectors which cannot be suction loaded with the equipment for

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

be tested using Method B in the apparatus shown in Figure 4 . The

load measuring equipment, load cell, manometer and so forth shall

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

An air bag as described in Paragraph 7.7 is placed under the

specimen to provide uplift for Case 2 tests.

7. 8. 3.1 Method A - The apparatus for Method A, Figure 3, consists of a series of vacuum lift cups (glass handling equipment) applied to

the glazing and attached to an articulated whiffle tree

arrangement.

Wind uplift is generally negligible for small spacings.

25
Crane Lift with Ram (Tension)

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

FIGURE 3. METHOD A - APPARATUS FOR NEGATIVE LIVE LOADS TEST (air bags for Case 2 only)

26
7. 8. 3. 2 Method B - For Method B, Figure 4, the apparatus consists of a rigid vacuum chamber with the collector forming one side of the

chamber and includes a vacuum device capable of providing the

required load.

7.8.4 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 such 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 Paragraph 7.12.

STEP 3 - Apply a load of 20 psf at a rate of 10 psf per minute.

For Case 2 tests this 20 psf load is applied simultaneously in

both suction and uplift for a total of 40 psf.

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 Paragraph 7.12.

STEP 6 - Apply a load of 40 psf at a rate of 10 psf per minute.

This is a total of 80 psf for Case 2 tests.

STEP 7 - Maintain the load for one (1) minute and then gradually

remove the load.

STEP 8 - Repeat Step 5.

STEP 9 - Apply a load of 50 psf at a rate of 10 psf per minute.

This is a total of 100 psf for Case 2 tests.

STEP 10 - Repeat Step 7.

STEP 11 - Repeat Step 5.

27
s

a a

q h

u

fO Oi ^

p 4-> p C •H o 0 cn > +jP

--P rH o

0) fd

f-H e 0

C q p p H 0 (U 3 U) XI p e c n u rO

0) a 0 X

> n3 Ph U

28

FIGURE

4.

METHOD

B

-

APPARATUS

FOR

NEGATIVE

LIVE

LOAD

TEST

(Air

baqs

for

Case

2

only.

)
STEP 12 - Continue the cyclic application of the loading to the

collector by increasing the applied load in 10 psf increments

(total of 20 psf for Case 2 tests) until some type of physical

damage is observed or a maximum load of 90 psf is obtained

(180 psf for Case 2 tests) . The leakage rate shall continue

to be performed at the end of each cycle.

7.8.5 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 A or B)

.

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

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

29
7.9 Longitudinal Loads

7.9.1 Purpose

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

collector and its mountings to withstand cyclic loads in the

plane of its longitudinal axis.

7.9.2 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 mounted in

the test apparatus in accordance with the manufacturer's normal

mounting instructions.

7.9.3

Apparatus

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

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

horizontally with the apparatus illustrated in Figure 5. When

tested by Method B, the collector is tested vertically or at an angle with the apparatus illustrated in Figure 6. The loading

equipment shall be capable of applying loads with an accuracy

of 1%.

7. 9. 3.1 Method A

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.

7. 9. 3. 2 Method B

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.

30
Hydraulic

Jack 0) u c

•H o > -H U -P 0) «3 Ui U I (U c a,

(Uu c

•H

O > -H U +j

(U

n

w P I OJ c a H o

E-i ww

EH01^12QOK

Eh

in§gH

Cm

31
FIGURE 6. METHOD B - APPARATUS FOR LONGITUDINAL LOAD TEST

32
7.9.4 Procedure

7. 9. 4.1 Method A

STEP 1 - Mount the collector on the test bed utilizing the

manufacturer's normal mounting method.

STEP 2 - Attach the loading device in such a manner that a load

will be imposed parallel to the test bed and through the center

of gravity 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

.

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

STEP 6 - Inspect collector for structural damage.

7. 9. 4.2 Method B

STEP 1 - The collector to be tested shall be mounted on a flat,

rigid, vertical wall as illustrated in Figure 6, or on a flat,

rigid, inclined wall that represents the normal mounting

installation position. Air 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.

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 center of gravity 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 collector for structural damage.

7.9.5 Data Requirements

Document applied loads and any structural damage or degradation

resulting from this test.

33
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 the

collector cover plate (glazing) to withstand impact forces from

hailstones or similar flying objects.

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

horizontally on the test bed by the mounting brackets or fixtures

supplied with the collector.

Apparatus

The apparatus shall consist of two (2) steel balls (1 in. diameter

and 1-1/2 in. diameter) and the equipment required to hold, aim and

drop the steel balls the required distance onto the specified

points on the collector glazing. The weights of the balls shall be

0.147 lb +1% for the 1 in. and 0.500 lb +1% for the 1-1/2 in.

Procedure

The test procedure consists of dropping the 1 in. steel ball

9.5 feet, and the 1-1/2 in. steel ball 14.5 feet onto the specified

points on the glazing of the horizontal collector.

STEP 1 - Support the collector in a horizontal plane beneath the

drop point. The collector shall be supported on a rigid surface

by means of normal mounting fixtures.

STEP 2 - The impact point on the specimen shall be at a point

six (6) inches from each of the two intersecting edges of the

glazing (see Figure 7).

STEP 3 - Apply an impact load by dropping the 1 in. steel ball

from 9.5 feet onto the specified point.

STEP 4 - Apply an impact load by dropping the 1-1/2 in. steel ball

on the same point from 14.5 feet.

STEP 5 - Repeat Steps 3 and 4 for two (2) additional impact points

on the specimen, if undamaged by previous impacts.

34
Impact Point

i.

6

"

Edge of Glazing

FIGURE 7. POINT OF IMPACT ON GLAZING

35
STEP 6 - Measure the depth of indentation and describe the damage

including cracking, breaking, fracture, tearing or puncture.

7.10.5 Data Requirements

Document any structural damage resulting from this test and the

impact load at which it occurred.
. 11

7.11.1

7.11.2

7.11.3

7.11.4

Static Over-Pressure Test

Purpose

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

collector to withstand excess pressure, resulting from variations

in supply source or malfunction of the system.

Test Specimen

The test specimen shall consist of a complete solar collector

panel assembly. Liquid collectors shall be prefilled with tap

water.

Apparatus

The apparatus consists of a hydrostatic pressure source or air

supply and necessary regulators to maintain the specified static

pressure. A pressure tap shall be installed in the collector

outlet port which shall be sealed and capped with a pressure

relief device set to a value within -0 to +10% of the specified

test pressure. For air collectors, the pressure tap shall be

connected to a water manometer which can be read accurately to

0.05 inch water column or a pressure gauge of equivalent accuracy

For liquid collectors, the pressure tap shall be connected to a pressure gauge which can be read accurately to 0.1 psi.

Procedure

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

STEP 2 - Attach the air supply or hydrostatic pressure source to

the inlet port of the collector.

STEP 3 - Increase regulated pressure to the level indicated below

Air Collectors - Two and one-half times the collector manufacturer's maximum recommended operating pressure, but not less than

1-1/4 inch water column. Maintain this pressure for a period of one (1) hour [7]

.

Liquid Collectors - One and one-half times the collector manufacturer's maximum recommended operating pressure, but not less than

25 psig. Close the inlet valve and hold the pressure for

15 minutes [1]

.

STEP 4 - Document any pressure drops indicated on the exit

pressure gauge and visible liquid leakage.

STEP 5 - Decrease the pressure to ambient.

37
STEP 6 - Check the pressure gauge or manometer for zero reading.

STEP 7 - Inspect the collector for evidence of structural damage.

7.11.5 Data Requirements

Documentation of applied pressure, structural damage, visible

liquid leakage, evidence of excessive air leakage, and if pressure

drop is observed, the rate of pressure drop.

38
7.12 Static Pressure Leakage Test

7.12.1

7.12.2

7.12.3

7.12.4

Purpose

The purpose of this test is to determine leakage and to indicate

damage induced by other tests in this test plan.

Test Specimen

The test specimen shall consist of a complete solar collector

panel assembly. Liquid collectors shall be prefilled with

tap water.

Apparatus

The apparatus consists of hydrostatic pressure source or air

supply and necessary regulators to maintain the specified static

pressure. A pressure tap shall be installed in the collector

outlet port which shall be sealed and capped with a pressure

relief device set to a value within -0 to +10% of the specified

test pressure. For air collectors, the pressure tap shall be

connected to a water manometer which can be read accurately to

0.01 inch water column or a pressure gauge of equivalent accuracy.

Air collectors shall be tested in accordance with UL Standard 181

[7]. An air meter accurate to within +0.50 cubic feet under the

conditions of test shall be placed between the air supply source

and test specimen. The meter is to indicate the total volume of

air supplied to the sample over the period of the test. For

liquid collectors, the pressure tap shall be connected to a pressure gauge which can be read accurately 0.1 psi.

Procedure

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 or hydrostatic pressure source

to the inlet port of the collector.

STEP 4 - Increase regulated pressure to not less than:

Air Collectors - One-half inch water column and maintain this

pressure for one (1) hour [7]

Liquid Collectors - One and one-half times the collector manufacturer's maximum recommended operating pressure, but not less than

25 psig. Close the inlet valve and hold the pressure for

15 minutes [1]

39
STEP 5 Liquid Collectors - Document any pressure drop indicated

on the exit pressure gauge [1].

Air Collectors - Document the volume of air required to

maintain the pressure during the period of the test.

STEP 6 - Decrease the pressure to ambient.

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

7.12.5 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.

40
7.13 Fire Tests

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.

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 E 108-75 [8] to perform the following tests:

A. Intermittent flame exposure.

B. Spread of flame

C. Burning Brand.

Collectors 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. 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

may be connected as recommended by 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 E 108-75 [8] tests:

A. Intermittent flame exposure.

B. Spread of flame.

C. Burning Brand.

41
STEP 1 - Assure collector is dry (contains no heat transfer fluid)

.

STEP 2 - Prepare test set-up in accordance with Reference [8]

.

STEP 3 - Conduct required tests in accordance with Reference [8]

.

7.13.5 Data Requirements

7.13.5.1 Description of test specimen and mounting procedure.

7.13.5.2 Document data concerning both the collector assembly and roof

covering materials for each of the tests in accordance with

Reference [8]

.

42
8.0

[ 1 ]

[ 2 ]

[3]

[4]

[5]

[ 6 ]

[7]

[ 8 ]

[9]

REFERENCES

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, Nov. 1976, NBS Report No.

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, Jan. 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, Feb. 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, NY 10017.

WATER PERMEANCE OF MASONRY, ASTM Standard No. E-514-74, Available

from American Society of 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.

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.

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.

SURFACE BURNING CHARACTERISTICS OF BUILDING MATERIALS, ASTM

Standard No. E-84-76a, Available from American Society of

Testing Materials, 1916 Race Street, Philadelphia, PA 19103.

43
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APPENDIX A

PROPOSED RATING CRITERIA

FOR FLAT PLATE SOLAR COLLECTORS

A-1. 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.

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

Collectors shall not exhibit a change in the product of

F„ ra (intercept) or F„U^ (slope) that would result in a 10% or greater decrease in thermal efficiency for the proposed

operating conditions (see Reference [1], Paragraph S-515-2 . 1 . 2 ) . 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-1
A- 6

.

Thermal Cycling Test (Paragraph 7.6)

A- 7 /A8

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.

Positive and Negative Live 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,

negative and combined live loads. (The values of U required for a specific application can be determined in accordance with [2] or

[3] 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 following

relationship

:

U = R^(l-av)

where: = 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 a

1 3.29

2 2.81

3 2.59

4 2.47

5 2.38

10 2.17

A2
A-9.

A-10.

A-10. 1.

The factor u may be taken from the literature or from auxiliary

tests. If variability data is not available a conservative

estimate for should be used.

If only one test specimen is used per test method and if i/ is

equal to 0.2 (this coefficient is given in the literature for

glass) , then

U = 0.34 Rm

The value of p 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 p 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 shall not exhibit visual evidence of structural

damage

Hail Loads (Paragraph 7.10)

General

The cover plates, lenses, and reflector surfaces of the solar

collector will have a high probability of withstanding the

impact forces of hailstones in most regions of the United States

if failure does not occur by dropping the 1 in. steel ball from

9.5 ft. This includes all regions with up to 2-4 mean annual

number of days with hail (see Reference [1] , Figure S-601-7)

The 1-1/2 in. steel ball dropped from 14.5 ft will apply to

regions with greater than 4 mean annual number of days with

hail. The impact forces applied by the steel ball to the

collector simulate the kinetic energy of a 1 in. or 1-1/2 in.

hailstone falling at its terminal velocity.

AA-10. 2. Rating Criteria

A-11.

A-12.

A-13.

A-13. 1.

The collector is acceptable for use in regions with up to 2-4

mean annual number of days with hail if no significant damage

(i.e., cracking, breaking, fracture, tearing or puncture) occurs

from the 1 in. steel ball drop, or regions with greater than

4 mean annual number of days with hail if no significant damage

(i.e., cracking, breaking, fracture, tearing or puncture) occurs

from the 1-1/2 in. steel ball drop.

Static Over-Pressure Test (Paragraph 7.11)

The collector shall not exhibit either of the following:

A. Visual evidence of catastrophic or structural failure

including rupture by breaks, tears, rips or other

openings

.

B. A pressure drop of 1% or more of the test pressure in

liquid collectors.

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 [7]

.

Liquid Collectors - A pressure drop 1% or more of the test

pressure or visual evidence of leakage shall not occur.

Fire Tests (Paragraph 7.13)

General

The collector shall not reduce the fire resistance of a Class C [8] roof assembly. The collector shall be effective

against light fire exposure, not readily flammable, afford

a light degree of fire protection, does not slip from

position, and does not 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.

A4
A-13.2. Rating Criteria

A-13.2.1 The collector must meet the requirements for a Class C rating

given in Reference [8] 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 shall any

portion of the collector be blown or fall off the

the test deck in the form of flaming or glowing

brands that continue to glow after reaching the floor

or 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 [9] for all insulation materials shall not

exceed the following values:

Plastic Foam 25

Loose Fill Insulation 50

Other Insulation Material 150

A-13.2. 3 Materials used as duct liners shall comply with the requirements

of Paragraph 5.3 of Reference [7] for Class 1 air ducts.

A5
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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 , and

Si

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

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

the following table.

Personal communication from J. E. Hill, National Bureau of Standards

B-1
TABLE B-1 TYPICAL COMPUTATION OF ALL DAY SOLAR COLLECTOR EFFICIENCY

HOUR OF THE DAY , SOLAR TIME

CALCULATION STEPS 6-7 7-8 8-9 9-10 10-11 11-12 12-1 1-2 2-3 3-4 4-5 5-6 UAlJji j 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,

t , °C

a 10 10 10 13 15 16 16 22 24 24 18 18

3. Incident radiation

on collector plane.

I^, W/m^, (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, & 3 2 15 38 42 46 46 46 43 42 18 2 1

5. Incident angle

between direct solar

beam and outward

drawn normal to ^ collector plane, 0 90 75 60 45 30 15 15 30 45 60 75 90

6. Incident angle modifier, determined in

accordance with

Sections 8.3.3 & 8.6

of ASHRAE 93-77 and

using the value of 0 from Line 5 .48 .82 .93 .97 1.0 1.0 .97 .93 .82 .48

1

i

7. Energy output from

2 collector, W/m , Line 3 x Line 4 x

I Line 6 - 2.0 56 245 357 457 474 443 350 239 39 - 2662

8. Collector thermal

efficiency.

Line 7/Line 3 HU]

Example: 32°N Lat.

42° Tilt

March - Clear Skies

B-2
NBS114A (REV. 7-73)

U.S. DEPT. OF COMM. BIBLIOGRAPHIC DATA

SHEET

1. PUBLICATION OR REPORT NO. NBSIR 77-1305

2. Gov’t Accession

No.

3. Recipient's Accession No.

4. TITLE AND SUBTITLE

PROVISIONAL FLAT PLATE SOLAR COLLECTOR TESTING PROCEDURES

5. Publication Date September 1977

6. Performing Organization Code

465.00

7. AUTHOR(S)

Solar Energy Program Team, Center for Building Technology

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. 4656505, Task 10

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

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

Energy Research and Development Administration

20 Massachusetts Avenue, N.W.

Washington, D.C. 20545

13. Type of Report & Period Covered

Interim

14. Sponsoring Agency Code

15. SUPPLEMENTARY NOTES

16. ABSTRACT (A 200-word or less factual sunimary of most si^ifleant information. If document includes a significant

bibliography or literature survey, mention it here.) 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 EKDA and HUD respectively. These test methods and

rating criteria do not, however, represent a consensus of industry and are therefore

provisional in nature. 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 Unlimited 19. SECURITY CLASS

(THIS REPORT)

21. NO. OF PAGES

1 ! For Official Distribution. Do Not Release to NTIS

UNCL ASSIFIED 35

1 1 Order From Sup. of Doc., U.S. Government Printing Office Washington, D.C. 20402, SD Cat. No. C13

20. SECURITY CLASS

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22. Price

Pt 1 Order From National Technical Information Service (NTIS)

Springfield, Virginia 22151 UNCLASSIFIED $4.50

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