www bzfxw com BRITISH STANDARD BS EN 1279 2 2002 Glass in building — Insulating glass units — Part 2 Long term test method and requirements for moisture penetration The European Standard EN 1279 2 200[.]
Terms and definitions
For the purposes of this European Standard, the terms and definitions given in prEN 1279-1:1998 together with the following apply.
3.1.1 standard laboratory conditions ambient temperature of (23 ± 2) °C and a relative humidity of (50 ± 5) %
3.1.2 standard moisture adsorption capacity capacity of a desiccant material to adsorb a quantity of moisture under controlled limit environment conditions
3.1.3 controlled limit environment conditions environment temperature 10 °C with a dew point temperature of - 5 °C, giving a relative humidity of 32,8 %
3.1.4 moisture penetration index amount of drying capacity consumed after standardised ageing conditions
3.1.5 accuracy precision of the test method itself within confidence limits of 99 %
Abbreviations
Symbols
I Moisture penetration index (can be expressed in decimal or in percentage terms);
The average value of the moisture penetration indices, denoted as I, is calculated from five measurements The mass of the empty, clean, and dry dish is referred to as mo The mass of the dish combined with the desiccant and the water adsorbed from air at 32% relative humidity is represented as mc The mass of the dish, desiccant, and both the initially adsorbed water and additional water adsorbed under specific climate conditions in the cabinet is denoted as mf The mass of the dish plus the desiccant and the initially adsorbed water is indicated as mi Finally, mr represents the mass of the dish plus the desiccant and the water adsorbed in equilibrium with a defined reference level of relative humidity or the mass of the dish plus dried desiccant at elevated temperatures.
Mm Mass of desiccant in mixtures with non-desiccant material;
Mt Total mass of desiccant when, for the purpose of testing, in a mixture with non-desiccant material, the non-
Tc Standard moisture adsorption capacity of desiccant;
Tc,av Average standard moisture adsorption capacity of desiccant Tc obtained over two measurements;
Tf Final moisture content of desiccant;
Tf,u Uncorrected final moisture content of desiccant;
Ti Initial moisture content of desiccant;
Ti,av Average initial moisture content of desiccant Ti obtained over four measurements;
The uncorrected initial moisture content of the desiccant, denoted as \$T_{i,u}\$, plays a crucial role in the testing process The temperature of the test specimens within the test cabinet is represented by \$\Theta\$ During the constant temperature phase, the temperature of the central test specimen is indicated as \$\Theta_c\$ In the high humidity and temperature cycling phase, the high temperature of the central test specimen is marked as \$\Theta_h\$, while the low temperature is denoted as \$\Theta_l\$ Lastly, \$\Theta_s\$ represents the temperature of the central test specimen as it transitions between high and low temperatures throughout the cycling process.
Moisture penetration index
Insulating glass units must perform effectively throughout their economically viable lifespan Consequently, specific values are assessed on test specimens subjected to the climate test outlined in this standard.
The average moisture penetration index I av over the five test specimen shall not exceed 0,20.
The breakage of glass does not indicate failure; instead, the average moisture penetration index (Iav) must be calculated based on a minimum of five units and a maximum of five units In cases where test specimens are broken, spare units should be utilized for accurate testing.
The unit with the highest moisture penetration index shall have an index value I not exceeding 0,25.
Edge seal strength
For the requirements on edge seal strength, refer to EN 1279-4.
Gas leakage rate
When the system description includes gas-filled insulating glass units, for additional testing and requirements on gas leakage rate, refer to EN 1279-3.
Principle
Insulating glass units undergo climate testing to assess their performance During this process, the initial and final dew points, along with the initial and final moisture content, are measured These measurements are then used to calculate the moisture penetration index, providing valuable insights into the units' durability and effectiveness.
Climate conditions in cabinet
The high humidity and temperature testing procedure includes two main phases: the first phase involves 56 temperature cycles lasting 12 hours each, ranging from -18 °C to +53 °C with a rate of change of 14 °C/h The second phase maintains a constant temperature of +58 °C for a duration of seven weeks, with specific high humidity conditions as outlined.
The exact specifications of the temperature, humidity and time, and their tolerances, are given in Figures 1 and 2.
1 56 temperature cycles of 12 h (is four weeks)
2 Interval of 2 h to 4 h for moving test pieces from one cabinet to a second cabinet when two cabinets are used
3 (1176 ± 4) h (seven weeks) constant temperature and a relative humidity of r.h ≥ 95 % Condensation on test specimen is allowed
Figure 1 — Overview of climate conditions in cabinet ΘΘ is the glass temperature of the centrally located test specimen - Temperature cycles start with the cooling part
During the temperature cycle, relative humidity can reach a maximum of 95% or higher However, during the colder phases of the cycle, this high humidity is temporarily disrupted, allowing for occasional condensation on the test specimen.
– Time intervals: t 1 = 5 h, t 2 = 1 h, t 3 = 5 h, t 4 = 1 h, t 5 = total cycle time 12 h ;
– Tolerance on time intervals: less than 1 min;
– Temperatures of the centrally located test specimen during cycle:
Figure 2 — Temperature/time and humidity/time relations in cycling stage
The process can be conducted in either a single cabinet or two separate cabinets If two cabinets are utilized, allocate up to 4 hours for transferring the test specimens between them for the second period.
The temperatures and tolerances shown in Figures 1 and 2 apply to the glass located centrally within the cabinet(s) Continuous recording of the temperature for this central test specimen is required, along with the relative humidity and air temperature measured at the optimal location within the cabinet(s) Any variations in temperature and relative humidity will be documented in the test report.
The glass temperatures of the other test specimens in the cabinet shall be:
In order to maximize uniform climate conditions throughout the cabinet(s), the distance between the vertically placed test specimens shall not be less than 15 mm.
Number, description and selection of the test specimens
A set of insulating glass units includes 15 test pieces that are representative of the system description outlined in prEN 1279-1 Each test specimen consists of two panes of 4 mm clear float glass.
The dimensions for EN 572-1 and EN 572-2 specify a length of (502 ± 2) mm and a width of (352 ± 2) mm, with a preferred gap of 12 mm, or as close to 12 mm as feasible if not manufactured While the cavity is ideally air-filled, alternative gases may be utilized Additionally, the construction details for the edges and corners must align with those of the units available in the market.
When the system description contains curved insulating glass units with a bending radius equal to or less than 1 m, the test pieces shall be curved as described in prEN 1279-1.
For mixtures of desiccant and non-desiccant materials that cannot withstand temperatures of 1,000 °C, the Karl Fischer method should be employed to measure moisture content, provided the method is verified for applicability Alternatively, the non-desiccant material can be substituted with an equivalent volume of desiccant.
When the system provides a mixture of desiccant with a non-desiccant material, incapable of withstanding 220 °C, the non-desiccant material shall be replaced by the same volume of desiccant.
After receiving the test specimens, condition them for a minimum of two weeks under standard laboratory conditions The initial dew point temperatures of the specimens, measured according to section 6.1, must fall within a specified range.
The maximum dew point temperature should be considered as 10 K below the manufacturer's specified value For dew point temperatures below -60 °C, it is recommended to use -60 °C as the standard reference.
Rank the test specimens based on their dew point values, starting with the highest dew point value as number 1 and concluding with the lowest dew point as number 15 Randomly assign numbers to units with dew point values below -60 °C Choose the units according to the specifications outlined in Table 1.
Table 1 — Designation of insulating glass units in climate tests
Unit number Designate units for:
7, 8, 9 and 10 Measurement of initial moisture content of desiccant (Ti)
4, 5, 6,11 and 12 Climate testing and measurement of final moisture content of desiccant (Tf)
2, 3, 13 and 14 Spare units to replace broken units for measurement of final moisture content of desiccant (Tf) (after climate testing)
1 and 15 Rejection or measurement of standard moisture adsorption capacity of desiccant (Tc) as required
Procedure
To begin the climate test, measure the initial moisture content (Ti) of the desiccant on the four selected test specimens as per section 6.2 Subject the five selected test specimens to the specified climate conditions outlined in section 5.2 For units lacking desiccant, determine the initial dew point temperature of the test specimens according to section 6.1, which allows for an equivalent value of Ti to be calculated in accordance with section 6.2.3.
To optimize time and costs during testing, the manufacturer or their representative can choose to expose spare units to climate conditions either from the start or only after a unit fails under those conditions.
To assess the need for periodic moisture penetration testing, it is advisable to conduct the periodic moisture penetration test as outlined in EN 1279-6 alongside this procedure.
Store the units for a minimum of two weeks under standard laboratory conditions.
Measure the final moisture content (Tf) of the desiccant in the five test specimens as per section 6.2 If the desiccant amount in the test unit varies from that of commercially available units, note the final moisture content accordingly.
Tf shall be corrected by the multiplier test in unit desiccant n descriptio system per as desiccant
Q is amount of desiccant in weight or in volume.
In cases where technical limitations prevent the desiccant quantity in test pieces from accurately reflecting the system description, testing may proceed with an alternative quantity However, it is essential to adjust the test results to derive a true I-value.
For units lacking desiccant, determine the final dew point temperature of the test specimens as outlined in section 6.1 This dew point temperature allows for the calculation of an equivalent value for \( T_f \) in accordance with section 6.2.4.
Determine the standard moisture adsorption capacity (Tc) as outlined in annex D If needed, assess the standard moisture adsorption capacity of the desiccant from the rejected units per section 6.2 For units lacking desiccant, establish Tc following the guidelines in section 6.2.4.
Calculate the average initial moisture content of the desiccant from the following equation:
When applicable, calculate the average standard moisture adsorption capacity of desiccant from the following equation:
Calculate the moisture penetration index, in fractions or in percentage, of each of the five selected or designated test specimens subjected to the climate conditions, from the following equation:
Calculate the average moisture penetration index from the following equation:
Insulating glass unit manufacturers must recognize the importance of test accuracy, as shown by proficiency testing results A proficiency test conducted with 10 laboratories revealed that an accuracy of better than ± 0.10 for the moisture penetration index I, when expressed as a ratio, or ± 10% absolute when expressed as a percentage, is achievable.
Measurement of dew point temperature
Any method is applicable when checked against the reference method given in annex A.
Measurement of moisture content
General
Moisture content values from different methods shall not be mixed.
NOTE There are three methods available for the moisture content measurements (Ti, Tf and Tc):
– the 950 °C drying method: applicable for desiccant in bulk;
– the Karl Fischer method: applicable for desiccant incorporated in organic sealing material;
– the partial pressure method: applicable for units without desiccant.
Although the final outcome, the moisture penetration index I, is independent of the method used, the moisture content values are not.
Moisture content of desiccant in bulk
Weigh an empty dish Prepare and collect desiccant from each designated unit:
– for the initial moisture content Ti, according to B.3;
– for the final moisture content Tf, according to B.3;
– for the standard moisture capacity Tc, according to B.4.
Weigh the dish and desiccant Dry desiccant according to B.2 and B.3 After cooling, weigh dish and desiccant. Calculate the moisture contents:
– initial moisture content: according to equation (B.1);
– final moisture content: according to equation (B.2) and eventual corrected value according to equation (B.4);– standard moisture adsorption capacity: according to equation (B.5).
Moisture content of desiccant incorporated in organic spacer
Prepare and collect organic spacer material containing desiccant, four samples, one from each side according to C.3, of each designated unit:
– for the initial moisture content Ti according to C.3;
– for the final moisture content Tf according to C.3;
– for the standard moisture capacity Tc according to C.4.
Weigh the samples Determine the moisture contents by applying the Karl Fischer method according to annex C.NOTE The method gives directly the moisture contents: Ti, Tf or Tc.
Moisture content in insulating glass units without desiccant
To determine the water vapor partial pressure corresponding to the dew point temperature, refer to Table 2 as outlined in section 6.1 The resulting value is labeled as Ti for the initial moisture content and Tf for the final moisture content.
The value of the water vapour partial pressure obtained for the limit environment conditions defined in 3.1.3, is designated Tc, and is equal to 402 Pa (dew point -5 °C).
Table 2 — The water vapour partial pressure as function of the temperature
Partial water vapour pressure °C Pa °C Pa °C Pa °C Pa
The test report shall evaluate the test in detail and shall include the following summary:
Name of test house, its address and logo.
Insulating glass units - Moisture penetration results according to prEN 1279-2
For details, see the test report
System conforms: YES NO (Delete whichever is not applicable)
NOTE Comparisons of moisture penetration indices of different insulating glass unit system are meaningless.
Reference method for dew point temperature measurement
General
This method is the standard reference for commonly used testing procedures in laboratories Comparisons are made using test specimens, as specified in section 5.3, which must be positioned vertically on their shorter edge.
This method does not claim to measure the dew point temperature with precision, as the exact deviation is uncertain, though it is estimated to be a maximum of 5 °C Nevertheless, it is favored for its reliability, reproducibility, and simplicity.
The dew point is indicated by water condensation on glass surfaces When measuring dew point temperature, the moisture condensed on the glass is subtracted from the free moisture, leading to a lower measured dew point temperature As the unit size decreases and the dew point temperature lowers, the moisture amount decreases, resulting in a greater deviation from the actual dew point temperature For standard-sized units, dew point temperatures below -60 °C show significant deviation; however, the moisture level is so minimal that these temperatures can be considered equivalent to -60 °C.
Apparatus and materials
– Cooling cell, in accordance with Figure A.1;
– Crushed solid carbon dioxide, for cooling;
– Alcohol thermometer with a range of at least from +30 °C to -70 °C, and with a limit deviation of ± 1 °C.
Procedure
To measure the dew point temperature, conduct the experiment under standard laboratory conditions as specified in section 3.1.1 Begin by placing the cooling cell on the cleaned glass surface at the center of the unit, using a few drops of ethanol to enhance conductivity Insert the thermometer into the cooling cell and fill it with ethanol to a height of 30 mm to 35 mm Gradually add crushed solid carbon dioxide to the ethanol, ensuring that the cooling rate does not exceed 2 K/min from approximately 20 K above the dew point Continuously monitor the internal glass surface in front of the mirror, and once condensation is observed, record the temperature of the cooling liquid as indicated by the thermometer; this temperature represents the dew point temperature.
4 Spring or screw, clip or tap
5 Glass mirror, silver coating and protective painting at back face a = (40 ± 2) mm b = (60 ± 1) mm c is the maximum 2 mm including painting d = (2 ± 0,1) mm e = (10 ± 2) mm f = (10 ± 2) mm g = (50 ± 1) mm
Figure A.1 — Dew point cooling cell and thermometer
Moisture content measurement according to the 950 °C drying method
Applicability
The measurement method is applicable for desiccant in bulk.
Apparatus, materials and preparatory work
B.2.1 Room conditions shall be standard in accordance with 3.1.1 Precautions shall be taken to minimize dust. The room should be a closed one so that traffic through the room is prevented.
B.2.2 Balance accuracy shall be at least ± 0,001 g.
B.2.3 Recommended dish and lid: a porcelain one as e.g illustrated in Figure B.1.
Figure B.1 — Illustration of a dish with lid Dimensions in mm
To ensure accurate measurements, clean and dry the dish and lid by washing them in distilled water, then dry them in an oven at 120 °C until they reach a constant weight Allow the dish to cool to room temperature before weighing it without the lid, recording the mass as \( m_o \) This procedure should be applied to all dishes at the start of each weighing series.
Initial and final moisture content
B.3.1 Remove the desiccant according to either a) or b) as follows: a) recommended procedure for removing desiccant, 1st alternative;
1) cut through the seal using a sharp knife;
2) remove one pane of glass Repeat for the second pane of glass;
3) separate the spacer parts when possible;
4) saw the spacer parts half through in the centre;
5) bend the spacer parts by hand over the dish and put desiccant in the dish;
6) retain 20 to 30 g from the total amount where possible, after mixing if necessary;
7) avoid splinters from spacer in the desiccant;
8) place the lid on the dish Transfer to weighing room;
9) weigh the dish and desiccant without the lid (mi for Ti determination, mf for Tf determination).
Operations 1) to 3) should be done within 5 min.
Operations 4) to 9) should be done within 3 min. b) recommended procedure for removing desiccant, 2nd alternative:
1) remove the seal over a number of millimetres sufficient for a template to be placed at approximately 60 mm from the corner;
2) place the template containing a hole with a diameter of 10 mm on the edge of the insulating glass;
To install the spacer correctly, drill a hole matching the diameter of the template hole on the back of the spacer It's crucial to shape the top of the drill to prevent twisting during the process Additionally, take care not to drill through the inner wall of the spacer into the insulating glass unit.
4) place the desiccant in the dish Discard the first 3 g to 5 g of desiccant, in order to prevent contamination from other materials;
5) retain 20 to 30 g from the total amount where possible, after mixing if necessary;
6) avoid splinters from the spacer, and other materials, in the desiccant;
7) place the lid on the dish Transfer from the work area to the weighing room;
8) eigh the dish and desiccant without the lid (mi for Ti determination, mf for Tf determination).
Operations 1) to 3) should be done within 5 min.
B.3.2 Place the lid on the dish and transfer to furnace Ensure that additional dust does not enter the dish, and ensure that no desiccant is lost from the dish.
B.3.3 Remove the lid and place the dish containing desiccant in the furnace Heat furnace from room temperature to 950 °C in (60 ± 20) min Keep the temperature at (950 ± 50) °C for a further (120 ± 5) min.
The optimal temperature for drying zeolites, silica gels, and their mixtures is 950 °C This high temperature ensures that the desiccant becomes inactive after drying, significantly minimizing the risk of errors.
To cool the desiccant to room temperature, remove the dish containing it, cover the dish with a lid, and place it in a desiccator After cooling, weigh the dish along with the desiccant, excluding the lid (mr).
B.3.5 Calculate the moisture contents in fractions or in percentages:
B.3.6 In the case of a mixture of desiccant with non-desiccant material, and that the non-desiccant material is replaced by desiccant, calculate the ratio R between the:
– mass of desiccant in the mixture (Mm) and
– the total mass of desiccant when the non-desiccant material is replaced by the same volume of desiccant (Mt). This ratio is:
The values derived from expressions B.1 and B.2 are referred to as Ti,u and Tf,u To determine the corrected initial and final moisture contents, Ti and Tf, multiply Ti,u and Tf,u by the ratio R.
Standard moisture adsorption capacity
Remove 20 g to 30 g of desiccant from the rejected units as specified in B.2.4, without weighing the dish at this stage If the desiccant is sourced from a drum, ensure it is placed on a dish that has been prepared according to B.2.4.
B.4.2 Prepare and maintain a relative humidity of 32 % in a desiccator by means of:
– prepare a saturated salt solution of Calcium Chloride crystals (CaCl2⋅6H2O) in water at (23 ± 2) °C by adding the crystals until no more dissolve;
– check if at least one crystal remains undissolved in the solution throughout the full test period;
– place the saturated solution in the bottom of the desiccator and close Allow to come to equilibrium for 24 h.
NOTE The created environment with the Calcium Chloride solution simulates the limit environment conditions defined in 3.1.3.
B.4.3 Humidify the desiccant to equilibrium adsorption at limit environment conditions:
Position the desiccant dish without a lid about 20 mm above the solution, ensuring it is supported to allow for unobstructed airflow Make sure the desiccant container is stable and does not touch the solution.
– reclose the assembly and leave for four weeks Check frequently throughout the test period to ensure that at least one crystal remains undissolved;
– after four weeks weigh the dish with desiccant within 30 s Return to desiccator and leave for a further week;
Quickly reweigh the dish and desiccant; if two consecutive measurements differ by more than 0.005 g, place them back in the desiccator over saturated Calcium Chloride solution and allow them to stand for additional weekly intervals until a constant mass is reached.
B.4.4 Designate the value of the constant mass mc.
B.4.5 Place the lid on the dish and transfer to the furnace Ensure that additional dust does not enter the dish, and that desiccant is not lost from the dish.
B.4.6 Remove the lid and place the dish containing desiccant in the furnace Heat the furnace from room temperature to 950 °C in (60 ± 20) min Keep the temperature at (950 ± 50) °C for a further (120 ± 5) min.
To cool the desiccant to room temperature, remove the dish containing it, cover the dish with a lid, and then place it in a desiccator After cooling, weigh the dish and desiccant without the lid to obtain the mass (mr).
B.4.8 Calculate the standard moisture adsorption capacity in fractions or in percentages:
Moisture content measurement according to the Karl Fischer method
Applicability
This method is based on ISO 760 The method is applicable for desiccant incoporated in organic seal material.
A proficiency test conducted across three laboratories has shown that using zeolite in bulk and zeolite incorporated in polyisobutylene and/or butyl can achieve accuracy levels similar to those obtained with the 950 °C drying method outlined in annex B.
For other types of desiccant or other types of matrix containing desiccant the applicability shall be verified.
Apparatus, materials and preparatory work
C.2.1 Room conditions shall be standard in accordance with 3.1.1 Precautions shall be taken to minimize dust. The room shall be a closed one so that traffic through the room is prevented.
C.2.2 Balance accuracy shall be at least ± 0,000 1 g.
C.2.3 The measurement method needs the following Karl Fischer (KF) apparatus and KF materials:
– KF calculator; and additionally nitrogen (N2+Ar>99,995 %, H2O