Determination of concentration time curves of the refrigerant R290 in leakage

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Air Conditioning and Air Quality

Am Technologiepark 1 D-45307 Essen, Germany Telefon +49 201 172-1304 Telefax +49 201 172-1606 aps@dmt-group.com www.dmt-group.com/de TÜV NORD GROUP

Determination of concentration time curves of the refrigerant R290 in leakage

simulations on multideck cabinets - - -

Report APS 2 – 00 005 16

CUSTOMER

Deutsche Umwelthilfe e.V.

Hackescher Markt 4 10178 Berlin

Consultant

DR. DANIEL COLBOURNE PO Box 4745

Stratford upon Avon Warwickshire CV37 1FE

Examined Specimen AHT, VENTO

Carrier, Optimer 2546

Examination performed by

Simon Roeser, Philip Pawlinski Dr. Dirk Renschen

Order No

RK 20658672

CONTENT PAGE

1 INITIAL SITUATION ... 3

2 SPECIMEN (MULTIDECK CABINETS) ... 3

3 TEST SET UP, TESTING EQUIPMENT AND TEST METHOD ... 4

3.1 TEST FACILITY ... 4

3.2 TEST EQUIPMENT ... 9

3.3 TEST PROCEDURE ... 14

3.3.1 Test setup in the tent ... 14

3.3.2 Placement of the nozzles for the leakage simulation ... 18

3.3.3 Testing scheme... 21

3.4 SAFETY - EXPLOSION PROTECTION ... 22

4 EXAMPLES OF TEST RESULTS ...23

4.1 EXAMPLE RESULTS OF TEST RUN 1 ... 23

4.2 REPEATABILITY OF THE R290 CONCENTRATION MEASUREMENTS ... 27

4.3 PRESENTATION OF ALL TEST RESULTS ... 32

5 SUMMARY ...33

ANNEX 1A ...34

ANNEX 1B ...35

ANNEX 2...36

ANNEX 3...37

ANNEX 4...52

1 Initial situation

DMT GmbH & Co. KG as independent testing institution was commissioned by the non- profit association “Deutsche Umwelthilfe e.V.”, Berlin, to perform a series of tests with multideck cabinets and R290 ( R290) as refrigerant. These examinations with chiller or multideck cabinets were carried out in February and March 2016.

R290 has excellent thermodynamic properties leading to high energy efficiency and a low environmental impact. But it has some different chemical properties than fluorocar- bon refrigerants; the primary difference is its classification as high flammability (A3) ac- cording to ISO 817.

As a basis for detecting the risk of explosion in the operation of such filled R290 cooling systems leakage simulation tests with R290 shall be performed by DMT. In defined rooms of different sizes determinations of the concentration time curves of the refrigerant R290 ( R290) shall be carried out within leakage simulations. Concentrations of R290 shall be put into relation to the lower explosion limit (LFL).

This Report describes exemplary the test procedure executed.

2 Specimen (Multideck cabinets)

Two different types of multideck cabinets were to be tested (picture 1a & b).

The first type was from (company) AHT (Austria), a “VENTO HYBRID” plug-in multideck chiller with following sizes: length 375 cm, height 238 cm and shelf width 126 cm.

Picture 1a) AHT VENTO HYBRID cabinet

This cabinet has a top-mounted condensing unit.

The second type was from Carrier, an “Optimer 2546” plug-in refrigerated multideck cab- inet with following sizes: length 250 cm, height 199 cm and shelf width 85 cm.

Picture 1b) Carrier “Optimer 2546” plug-in refrigerated multideck cabinet

3 Test set up, testing equipment and test method

To examine the leakage behaviour of cabinets with R290 as natural refrigerant main tar- get was to create a test setup which ensures a (repeatable and) reproducible test proce- dure. Therefore, these tests were performed as leakage simulations in a purpose-built tent with the opportunity to create variable room sizes for the different tests. This tent was set up inside a hall to keep the environmental conditions quite constant. For all tests the same sensors and test conditions were used. In the following the details are de- scribed.

3.1 Test facility

Testing was performed in a tent inside of a hall with outer dimension of 32 m length, 11.8 m width and roughly 9 m height (drawing in pic. 2a). The tent was set up in the front part of the hall (designation “E01” in pic. 2). The dimensions of the tent were 10 m x 4 m x 2.5 m (l x w x h). A drawing of the tent (upper part – top view; lower part – view longitu- dinal side) is shown in picture 2b. With the help of a “partition wall” within the tent the dif- ferent room sizes could be realized (10 m², 20 m² & 40 m²).

Picture 2a) Sketch of Test Hall B1, Horizontal Projection

The building has a folding gate in the front (bottom line of the sketch).

Picture 2b) Sketch of tent (upper part – top view; lower part – view longitudinal side)

The total volume of the tent was 100 m³. The rigid construction of the tent was made from square-shaped timber; the walls of the tent were made from 0.4 mm PE foil which was fixed to the timbers and gas tight. The foil intersections were air tight glued with heavy in- dustrial tape. The tent had two zipper doors, one zipper door on each broad side. The closed zippers showed no visual gaps against bright light. Therefore, the “basic” assem- bly was gas tight. Nevertheless, to be able to ventilate the tent for air exchange between the tests in the roof a hole was cutted (pic. 4g). This hole was covered with a coalescer filtermedia as cover and convection blocker. The leakage gases R290 and CO2 are heavier than air. As long as there is no ventilation (or convection) in the tent, there will be no significant gas loss.

Photos from the test hall and tent are shown in pictures 3a to 3h.

Pic. 3a) Test hall: front view

Pic. 3b) Test hall: back and side view

Pic. 3c) Test hall front with open front door and

tent long side Pic. 3d) Tent long side with look behind the zipper door of the test tent

Pic. 3e) View from outside the hall to the tent front with cabinet in between

Pic. 3f) Inside tent with view to front and cabinet

Pic. 3g) Tent roof

Pic. 3h) Tent back side with view to rolling door on the right side of the test hall

3.2 Test Equipment

The following measurement and testing equipment components were used for the leak- age simulation tests:

- Test gas R290 from a pressurized bottle (pic. 4a). Within testing a primary pres- sure of 5 bars was adjusted by the pressure-relief valve.

- Calibrated mass flow controller (MFC) Series 358 (pic. 4b). It is a „DIGITAL PRESSURE REGULATOR” from company ANALYT-MTC GmbH for dosage of the R290 gas.

o Volume rate control and measurement was done with a calibrated mass flow controller (which uses the differential drop across a laminar flow ele- ment for determination the exact flow rate).

o Volume rate range: 0 to 100 l/min

o Gas selection between 20 different gases o Calibration includes R290 and CO2

o Precision: ± 0.2 % Full scale o Response time: ≤ 100 ms

Calibration of the mass flow controller for R290 was verified by DMT: After a release of 3 x 300 g of R290 according the MFC the pressurized gas bottle lost 900 g (± 10 g).

Within testing there were no indications that at the measurement point (MFC) the R290 was not totally transformed to the gas phase.

- “Nozzle to simulate leakage of a tubing”

Nozzles were used to release R290 in the cabinet to simulate a leakage in a tubing of the refrigerant circle. They generated a gas stream comparable to the situation when a leakage occurs by a fissure in a tubing. The different nozzles were built from brass with a drilled hole. Diameters of the different nozzles were: 0.7; 1.0; 1.5

& 2.0 mm (pic. 4c).

- R290 measurements at different locations within the tent were performed with:

10 calibrated IR-sensors (GfG, Dortmund, Germany; pic. 4d – left side) o Intrinsically safe IR transmitter for explosion protection

o ATEX II 1G Ex ia IIC T4 Ga C0158 (can be used in Ex zone 0) o Temperature, moisture and pressure compensation

o Patented 4-beam 4-wavelength technology

o Measuring range: 0 to 100 % LFL (lower explosion limit) o Gas supply: Diffusion through membrane

o Repeatability: ≤ 0.5 % of measurement range and up to 10

pic. 8d – right side)

o Response time < 10 s

o Measuring range: 0 … 6 Vol. %

o Repeatability: ≤ 1 % of measurement range

- Data Aquisition

Each IR-sensor was connected with an ATEX-box (safe power supply for the sen- sor). Theses boxes were located outside of the tent and connected to an A/D con- verter which again was plugged via a LAN connection to a personnel computer in- stalled in the control room below the test hall (pic. 8e).

- Ventilation of the tent (Removal of R290)

After end of a test run the „ R290-contaminated“ air from the tent was sucked out of the tent by an explosion proof fan (TFV 100 radial fan EX) and blown in the envi- ronment outside of the test hall (pic. 4f).

Fresh air was sucked in the tent through a hole in the roof, which was covered by a coalescer filter-media as blocker for thermal convection (pic. 4g)

Pic. 4a) Control room with two laptops, pressur- ized R290 bottles and further test equipment

Pic. 4b) Calibrated mass flow controller

Pic. 4c) “Simulated leakages tubes” (Nozzles)

Pic. 4d) Two Calibrated Sensors for R290 measurement

Pic. 4e) Blue boxes “ATEX-box”, Red box in the lower part “A/D converter”

Pic. 4f) TFV 100 radial fan EX

Pic. 4g) Hole in the roof with coalescer filter (white) as cover and convection blocker

All components to release R290 in the cabinets (Pressurized R290 bottle, mass flow control- ler and nozzle) were connected by flexible, pressure stable and tight tubes. The mass rate of R290 which was released was controlled by the MFC via the A/D-converter which was con- trolled from a laptop. The IR-sensors were controlled and the data acquired from the same laptop. The thermal conductivity sensors (FTC) were controlled and its data acquired by a further laptop. The connection scheme is shown below in figure 1.

Figure 1) Connection scheme for R290 leakage simulation tests

3.3.1 Test setup in the tent

A comparable test setup for both cabinets was planned.

The test setup for the sensors should be as shown in figure 2.

Figure 2) Positioning of the test cabinet (grey) and the sensors (red) in a test room

In this figure the positions are shown schematically. “Floor” means sensor was posi- tioned on the floor level and e.g. “room centre, 1 m” that the sensor was positioned in the room centre in 1 m height by means of a tripod.

The sensor position “Beneath unit, 1 m (when applicable)” was deleted because there was no sufficient space for the ATEX-proved sensors.

The first type cabinet had a top-mounted condensing unit (“VENTO HYBRID” from AHT) and a size (l x h x w) of 375 cm x 238 cm x 126 cm. Due to this very big dimen- sions for this cabinet it could only be tested in the 20 m² and 40 m² room sizes.

First it was positioned with its back to the wall in the centre of the broad side to the test room (pic. 5a). Afterwards it was equipped with shelfs and filled with boxes to simulate the conditions in a supermarket (pic.5b).

In this picture 5b the tripod can be seen in front of the cabinet and equipped with 3 sensors (see pic. 4d): on floor level (blue IR sensor), 1 m (grey FTC sensor) and 2 m (again FTC). In this picture ropes can be seen which were used for test 21 (Annex 1,

test matrix), when two doors in the middle were opened 1min after start of leakage simulation (pic. 5c).

Some tests were made with a simulated roof top cover (pic. 5d) to examine the effect of such covers.

Cabinets were maximally loaded to minimise internal free volume and thus lead to pessimistic scenario (e.g. pic. 5b).

All tests were made without operation of the refrigerator. For some tests fans were in operation to examine the effect of mixing the R290 with the room air.

Pic. 5a) Cabinet with a top-mounted condensing unit as delivered

Pic. 5b) Cabinet with a top-mounted condensing unit before testing

Pic. 5c) Cabinet as in pic. 5b but closer

Pic. 5d) Again cabinet with top-mounted condensing unit but with roof cover

The test setup for testing the Carrier “Optimer 2546” plug-in refrigerated multideck cabinet was comparable (pic. 6a). Due to the smaller size of this cabinet with base- mounted condensing unit (l x h x w: 250 cm x 199 cm x 85 cm) tests could be per- formed in the 10 m² test room, too (pic. 6b).

Pic. 6a) Cabinet with base-mounted condensing unit in the 20 m² test room (broad side)

Pic. 6b) Cabinet with base-mounted condensing unit in the 10 m² test room (narrow side)

3.3.2 Placement of the nozzles for the leakage simulation

The different types of nozzles which were used for the leakage simulations are shown in picture 4c (nozzles of different drill hole sizes).

Preparing the different tests each time a nozzle had to be positioned as described in the test matrix to the according leak locations in both cabinets.

In pictures 7a - d the installation of the nozzles in the Carrier cabinet with base- mounted condensing unit are shown.

Pic. 7a) Cabinet Base CU with CRB (condenser return bend), RH (right hand) Leakage Point

Pic. 7b) Cabinet Base CU with ERB (evaporator return bend), RH, before installation

Pic. 7c) Cabinet Base CU with ERB

(evaporator return bend), RH, with installed nozzle (center) and supply pipe on right side

Pic. 7d) Cabinet Base CU with ERB (evaporator return bend) and nozzle behind cover

In pictures 8a - 8f the installation of the nozzles in the AHT cabinet with top-mounted condensing unit are shown.

Pic. 8a) Cabinet Top CU with CRB (condenser return bend) RH (right hand) Leakage Point

Pic. 8b) Cabinet Top CU with CRB (condenser return bend) RH (right hand) Leakage Point

Pic. 8c) Cabinet Top CU with nozzle located in the CU unit (center)

Pic. 8d) Cabinet Top CU, the supply pipe of the nozzle enters the unit through the hole in the cover (upper part)

Pic. 8e) Cabinet Top CU with ERB with installed nozzle (center) and supply pipe entering the housing from the bottom

Pic. 8f) Cabinet Top CU with ERB (evaporator return bend)

In pictures 9a & b the installation of a nozzle in a mock-up (cardboard box) on the top of the Carrier cabinet (base-mounted condensing unit) is shown. This mock-up was used for leakage simulations in a top CU in the 10 m² room.

Pic. 9a) Carrier cabinet (Base CU) with mock-up as a top CU unit from cardboard, supply pipe on the right

Pic. 9b) Mock-up unit from cardboard, nozzle in the center (iron weight on the right to load the mock up

3.3.3 Testing scheme

The testing schemes were developed from discussions amongst DMT, DUH, D. Colbourne and IEC SC61C WG4.

In table 1) the different variables or parameters of both test matrix are summarized with the used values or descriptions.

Remark: *) In parentheses are numbers of fans used for testing Table 1) Variables of the test matrix

Between the tests the tent was ventilated (contaminated air extracted) for air ex- change. The extraction was monitored and stopped at a R290 LEL level of ≤ 1 %.

The individual test matrix for the AHT top CU cabinet and the Carrier base mounted CU cabinet measurements are shown in Annex 1 and 2.

To avoid any explosion within testing several general precautions and countermeasures were made. Base of these precautions and countermeasures was an expert’s report to explosion prevention (Report 20658672: Explosionsschutzkonzept gemäß § 6 (9) 2. Gef- StoffV für einen Versuchstand zur Untersuchung von Leckageszenarien an Kühlgerä- ten). This expert report was made by the specialists of the DMT department “Fire and explosion protection”.

This expert’s report included:

 Review and Assessment of Material Properties

 Measures to prevent hazardous explosive atmospheres

 Precautions against ignition

 Measures for reduction of explosion effects to a safe level

 Organizational explosion protection measures

Examples of precautions and countermeasures for explosion protection:

 Several thermal conductivity measurement sensors were placed around the tent to monitor a possible leakage of R290 in the surrounding. Alert level were indi- cated automatically in the control room.

 No persons stayed in the test hall during the measurements.

 The control office was located one floor below the test hall.

 Access of unauthorized and untrained persons was prohibited.

 The released amount of R290 was controlled continuously by online monitoring the concentration in the tent by the test personnel.

 Manual closing of the R290 supply and start of the extraction of R290 from the tent after fault-related test stop or completion of test from the control room.

 Avoidance of electrostatic charges within testing (no opening of the zipper doors before air extraction after completion of test).

 Use of fans for the multideck cabinets were built classified as „II 2 G Ex d e ib IIB T3 Gb“.

 A risk assessment of the manufacturer of the fan was made for this leakage test.

 People involved in testing were instructed how to behave according the explosion protection rules listed in expert report.

4 Examples of test results

All test measurement results from the different sensors were collected in excel sheets. The R290 concentrations were transformed to %-values of the according lower explosion level (LFL) from R290 (propane: 2.1 % v/v; NFPA). For each test run these transformed data of all sensors were written for the same time scale in one excel-sheet. All raw data were given from DMT to the consulter of DUH for further data analysis.

4.1 Example results of test run 1

Before a test run was started all parameters were adjusted as described in the example from the following table 2 (extract of the test matrix of the Carrier cabinet with base CU as shown annex 2).

Test no Room (m²) Release

mass (g) Cabinet Cabinet po-

sition Leak location Condenser airflow

Evaporator

airflow Doors

1

10 150 Base CU

(C)

Narrow end, centre

Evap return

bends Off Off None

2 Cond return

bends Off Off None

Test no Kick-plates CU cover Roof cover Mass flow (g/min)

Release time (s)

Measure- ment time

[min]

Remark

1 None None None 30

5 14

Overall baseline

2 None None None 30 Overall baseline

Table 1) Extract test 1 & 2 of the test matrix of the Carrier cabinet with base CU

With these settings test 1 (and 2) were performed. Sensors were positioned (see fig. 2) and numbered as shown in figure 3.

Figure 3) Numbering of the sensor positions

The according data for the first 3 min at measurement point 1 (MP 1) are listed in tab. 2. At MP 1 (0.5 m distance to the cabinet) IR sensor 1 was detecting the R290 concentration in parallel with a thermal conductivity sensor (FTC5).

Table 2) Extract measurement results of test 1 (Carrier cabinet with base CU)

The resulting curve of the concentration (expressed in percent of the LFL) against time for IR sensor 1 is plotted in figure 4a. The plot of the comparable curve from thermal conductivity sensor FTC5 is shown in fig. 4b.

Hour Duration Mass flow controller V set [l/min]

Mass flow controller V as-is [l/min]

IR sensor [%UEG]

Measurement Point 1

FTC5@MP 1 [%UEG]

10:50:01 00:00:01 0 0,1 0 0

10:50:06 00:00:06 0 0,1 0,1 0

10:50:11 00:00:11 0 0,1 0,1 0

10:50:16 00:00:16 0 0,1 0 0

10:50:21 00:00:21 0 0,1 0,1 0

10:50:26 00:00:26 0 0,1 -0,1 0

10:50:31 00:00:31 15 0,1 0 0

10:50:36 00:00:36 15 14,8 0 0

10:50:41 00:00:41 15 15,1 0,1 0

10:50:46 00:00:46 15 15,2 0,1 0

10:50:51 00:00:51 15 15,2 0 0

10:50:56 00:00:56 15 15 0 0

10:51:01 00:01:01 15 15 0,1 1

10:51:06 00:01:06 15 15 0 3

10:51:11 00:01:11 15 15,1 -0,1 6

10:51:16 00:01:16 15 15 0,9 10

10:51:21 00:01:21 15 15,1 3,4 13

10:51:26 00:01:26 15 15 5,4 18

10:51:31 00:01:31 15 15,2 7,1 26

10:51:36 00:01:36 15 15,3 9,4 31

10:51:41 00:01:41 15 15,1 12,7 30

10:51:46 00:01:46 15 15,2 15,3 30

10:51:51 00:01:51 15 15 18,3 33

10:51:56 00:01:56 15 15,1 22,4 35

10:52:01 00:02:01 15 15,1 26 36

10:52:06 00:02:06 15 15,1 28 38

10:52:11 00:02:11 15 15 30 39

10:52:16 00:02:16 15 15,1 31,3 38

10:52:21 00:02:21 15 15,1 33,5 40

10:52:26 00:02:26 15 15 34,7 41

10:52:31 00:02:31 15 15,1 35,4 43

10:52:36 00:02:36 15 15,1 35,8 43

10:52:41 00:02:41 15 15,1 36,8 43

10:52:46 00:02:46 15 15 37,5 41

10:52:51 00:02:51 15 15 39,7 40

10:52:56 00:02:56 15 14,8 40 42

10:53:01 00:03:01 15 15,1 41,4 43

Figure 4) Concentration time curve of the leakage simulation test 1 (IR sensor 1)

Figure 4b) Concentration time curve of the leakage simulation test 1 (FTC sensor 5)

As can be seen from tab. 2 after 31 s the mass flow controller was switched to 15 l/min re- lease of R290 (V set [l/min]). After the next time step of 5 s it was indicated that this flow was realized (V as-is [l/min] with a value of 14.8 l/min). After further 25 s R290 is indicated from

the thermal conductivity detector FTC5 (00:01:01) with a rough value of 1 % LFL. After fur- ther 15 s IR sensor 1 is indicating R290, too (00:01:16 with 0.9 % LFL).

Comparing the concentration values of both sensor types (fig. 4a & b) shows advantages and disadvantages of both sensor types. The thermal conductivity detector reacts faster to a change of the gas concentration. The IR sensor shows a delayed increase and decrease due to a membrane around the measurement cell which is necessary for explosion protection of this sensor. An advantage of the IR sensor is the higher sensitivity (smother curve) and lower detection limit. Another disadvantage is a technical set for an upper detection limit at beneath 100 % LFL. The FTC sensor is not restricted to the 100 % LFL level and was therefore, used at critical measurement points as sensor type to measure concentration far above the 100 % LFL level.

After 5 min release time the R290 release in the cabinet was stopped. 10 min after starting the test the air of the tent was extracted and exhausted to the outside of the test hall. This can be seen in fig. 5 for the concentration time curves of all sensors. 13 min after starting test 1 all measurements were stopped.

Figure 5) Concentration time curves of the leakage simulation test 1 (all sensors)

Especially for lower concentrations (below 30 % LFL) the IR sensor is more precise than the FTC.

To examine the risk potential by potential leakages in a cabinet in closed rooms the meas- ured concentration times curves in dependence of the location in the tent are very valuable.

4.2 Repeatability of the R290 concentration measurements

To examine the repeatability of this test method several tests under same conditions were repeated. For this examination in the 20 m² tent a diffusor was placed and R290 released.

Pictures of this diffusor are shown in pic. 10a & b and for the test setup in pic. 10c & d.

Pic. 10a) Diffusor setup: bottom of the bucket with holes for equal gas release

Pic. 10b) Diffusor setup: bucket with cotton as diffusor material; in the centre a smaller jar in which the tube to the R290 pipe is connected

Pic. 10c) Diffusor hanging at a stand Pic. 10d) Diffusor located at the narrow wall of the 20 m² room; sensors placed according scheme fig. 6

The scheme of the sensor positioning for this diffusor test is shown below in figure 6.

Figure 6) Scheme of the diffusor test setup

The according measurement schedule is shown in table. 3.

Table 3) Test schedule of the repeatability test with the diffusor

The data for all 4 test runs for one measurement point or location are shown in comparison in the following figures 7a to 7g for several measurement points (MP).

Sensors from MP1 to MP10 are type infrared (IR) and MP 11 & 12 thermal conductivity (FTC).

Differences between the scatter of the curves of the four repeated runs may derive from the sensor type and distance from the diffusor (release point), position and height in the room.

To examine this for all sensors at the different measurement points the average at a time point where roughly a 50 % LFL value occurs were selected. For this moment beneath the average the standard deviation and the relative standard deviation were calculated (Tab. 4).

Test no Room (m²) Release m ass

(g) Unit Unit base

install height Unit position

-1 20 1500 Diffusor 1.8 m Broad w all,

m iddle

Test no Leak location Unit airflow Louvre Mass flow

(g/m in) Rem arks

-1 Diffusor Off - 60 Repeatablity: 4

x (-1/1 to -1/4)

Figure 7a) Four concentration-time curves of the diffusor test at MP 1 (0.5 m from diffusor)

Figure 7b) Four concentration-time curves of the diffusor test at MP 5 (1 m from diffusor)

Figure 7c) Four concentration-time curves of the diffusor test at MP 7 (2 m from diffusor)

Figure 7d) Four concentration-time curves of the diffusor test at MP 9 (4.5 m from diffusor)

Figure 7e) Four concentration-time curves of the diffusor test at MP 10 (5 m from diffusor)

Figure 7f) Four concentration-time curves of the diffusor test at MP 11 (2.5 m from diffusor) Start air ex-

haust of tent

Figure 7g) Four concentration-time curves of the diffusor test at MP 12 (2.5 m from diffusor)

Table 4) Comparison of the scatter (RSD) between different measurement points

A comparison of the data in tab. 4 gives no clear answers. It seems to be that the sensors positioned nearer to the diffusor (MP 5 & 1) have less scatter than for MP 9 & 10. This be- comes clearer comparing the curves (7a & b with 7d & e). MP 7 shows in tab. 4 a quite high RSD (20 %). But this is caused by a strong deviation of the curve from run 3 (MP 7-3) in fig.

7c. After reaching values of > 60 % LFL after 3 min the scatter is quite low between the dif- ferent curves.

The different concentration-time curves from MP 11 (FTC sensor) are showing a higher scat- ter below 80 % LFL (tab. 4 23 % RSD after 15 min) but are approaching quite similar values after 20 min. Only MP 12 which is positioned 2 m above floor level shows especially after 20 min an increasing scatter. This is probably caused by fluctuating R290 levels in that height.

After 30 min the R290 loaded air was extracted from the tent.

Measurement

Point Sensor type Distance to release point [m] / Height [m]

Average point in time

Average [%

LFL]

Standard deviation [% LFL]

Relative standard deviation [%]

1 IR 0,5/0 2 min 46,7 6,4 14

5 IR 1/0 3 min 53,0 3,8 7

7 IR 2/0 2 min 50,8 9,9 20

9 IR 4,5/0 5 min 51,6 7,9 15

10 IR 5/0 7 min 53,1 7,8 15

11 FTC 2,5/1 15 min 51,3 12,0 23

12 FTC 2,5/2 25 min 17,5 5,7 32

In the figures 7a to 7e all IR sensors are showing a mixture between a flat line and a “squig- gle” reaching the 100 % LFL level. This irregular behaviour of the IR gas sensors during the R290 measurement has a technical reason.

As this IR sensor is designed to be used as a stationary sensor for gas monitoring it would not regularly face gas concentrations higher than 100%. But the very high resolution and pre- cision beneath the ATEX certificate were the reasons to use this detector. Due to an alarm- control it will set its analogue output to a value below 0% (e.g. to switch on an alarm horn).

To prevent this behaviour DMT reprogramed the measurement software, so values below 0 % appear as 100 % to keeps the concentration at the upper limit. Because the sensor is quite slow it is very difficult for the software to clearly identify this case, so a “jumping” or

“squiggle” appears at concentrations near 100%.

4.3 Presentation of all test results

In annex 1 the measurement matrix for the Top CU multideck cabinet is shown. The accord- ing concentration time curves of all room positions summarized for one test run in a graph are shown for all these test runs in annex 3 (figure 8a from test no. 17 to fig. 8ab from test no. 47).

The comparable graphical presentation of all test results as concentration time curves for the Base CU cabinet (matrix from annex 2) are shown in annex 4 (figure 9a from test no. 1 to fig.

9v from test no. 50).

5 Summary

In this report the testing conditions for simulated leakage tests with multideck cabinets are described.

All tests were performed under strict safety regulations and precautions because R290 is a highly flammable refrigerant. Despite the limitations caused thereby and especially in view of the sensor systems which can be used as online monitoring system, the resulting data could be used as expected for a subsequent risk assessment of cabinets for usage with several hundreds of gram of R290.

Essen, June 21, 2016

_______________________________ _________________________________

Dr. D. Renschen S. Roeser

(Head Product Assessment Refrigeration & Air Quality) (Technician Product Assessment Air Quality)

Annex 1a

Measurement Matrix Top CU (A)

Test noRoom (m2)Release mass (g)CabinetCabinet positionLeak locationCondenser airflowEvaporator airflowDoorsKick- platesCU coverRoof coverMass flow (g/min)Release time (s)

Measurem ent time [min]Remark 17OffOffOpenOnOnOff30 18OffOffOpenOffOnOff30 19OffOffOpenOn*OnOff10- 20OffOffClosedOn*OnOff10- 21OffOffClosedOn*OnOff30The two doors in the middle opened 1min after leakage; Fan started 4:30 min later 22OffOnClosedOn*OnOff30- 23OffOnOpenOn*OnOff30- 24OnOffOpenOn*OnOff30Effect of cond airflow on leak from evap 25On (x1)OffClosedOn*OnOff6018,0Fan #3 on (this cabinet has 6 condenser fans) 26On (x 2)OffClosedOn*OnOff6019,0Fans #2 + #5 on 27On (x 3)OffClosedOn*OnOff6020,0Fans #1 + #4 + #6 on On (x 4)OffClosedOn*OnOff60- (Was not done because previous test Cf < 12 g/m3) 28OffOffClosedOn*OnOff105060- 29OffOffClosedOn*OnOff3016,730- 30OffOffClosedOn*OnOff608,318- 31OffOffClosedOn*OffOff30- 32OffOffClosedOn*OffOn30- 33OffOffClosedOn*OnOn30- 34OffOffClosedOn*OnOff30Add polystyrene panel to CU corner to divert 35OffOffClosedOn*OnOff30- 37Condenser return bendsOffOffClosedOn*OnOff3030- 36Room centreCU housingOffOffClosedOn*OnOff30Move to centre of room (see test with top CU C)

16,7 20500top CU (A)

Broad side, centre

Evaporator return bends CU housing

8,3 16,7

25,0

30,0

Matrix Top CU Determine kick-plate case with the highest Cf 5060 16,730,0

Annex 1b

Measurement Matrix Top CU (A)

Test noRoom (m2)Release mass (g)CabinetCabinet positionLeak locationCondenser airflowEvaporator airflowDoorsKick- platesCU coverRoof coverMass flow (g/min)Release time (s)

Measurem ent time [min]Remark 38OffOffOpenOn*OnOff10100120- 39OffOffOpenOn*OnOff3050- 40OffOnOpenOn*OnOff3050- 41On (x3)OffClosedOn*OnOff6045(i) Start with max no fans from 20 m2 room. (Fans #1 + #4 + #6 on) 42On (x 4)OffClosedOn*OnOff6030(ii) If Cf < 12 g/m3, then do test with one fewer fan. But if Cf > 12 g/m3, then do test with one more fan. (Fans #1 + #3 + #4 + #6 on) 43OffOffClosedOn*OnOff10100110- 44OffOffClosedOn*OnOff3033,350- 45OffOffClosedOn*OnOff6016,731- 46Evaporator return bendsOffOffOpenOn*OnOff30- 47Condenser return bendsOffOffClosedOn*OnOff30-

Matrix Top CU 75033,338

1000 top CU (A)Broad side, centre

Evaporator return bends33,3 Condenser return bends

16,7 40