>< J: c.n» ISSN 1324-9479 JOURNAL OF THE AUSTRALIAN ASSOCIATION OF GLASS ARTISTS - ---- - --- ------------------------~ . .. I Editorial n Graham Stone 2 AusgLass I Hot Glass Burners and Controls 0 ~ss~ ,tn4~ Mark Brabham 3-7 Mag I The Gippsland Connedion ::s Christmas 195 Ivana Jirisek 8-9 Edition r+ I Glass Durability Testing Henry Halem 10-11 tD I Exhibition Review Rob Knottenbelt 12-13 ::s I David Wright's Shabbat Window r+ Graham Stone 14 I Letter to Members ua Linda Fraser 15 Correspondence 16 - Postcards From•.• 17 Glass News 18-19 Front Cover I Exhibitions 20 Nedscape by Henry Halem, 1995. This drawing is one of a series I European Glass '97 Gerie Hermans 21 of works on paper and in glass inspired by Sidney Nolan and Book Review: Glass Notes the whole Kelly legend. Graham Stone 22 Editorial Committee Magazine Ausglass Graham Stone Chairperson Letters and Correspondence to: Jan Blum (Secretary) Mies Grybaitis Secretary Graham Stone (Editor) PO Box 915 Cold Glass Workshop Leichhardt NSW 2040 Dick Stumbles Meat Market Craft Centre Ph/Fax (612) or (02) 5641398 Kim Lester Advertising 42 Courtney Street Please note the contact Rosy Green Distribution North Melbourne VIC 3051 for membership enquiries Fax (613) or (03) 9329 2272 and address changes: Tactix Design Design & Production Advertising Maggie Stuart Ph. (6142) or (042) 84 7844 Gerie Hermans Dick Stumbles Board Brenda Page Members 54 Green Island Avenue Vaughan Bryers Mount Martha VIC 3934 Ph. (6159) or (059) 755852 The views expressed in Ausglass Magazine are not necessarily the views of the Ausglass National Executive or the Magazine Board. - It's unfortunate that Linda Fraser Graham Stone has had to resign as President of Ausglass. (Her letter to you appears in this issue.) Nevertheless, the National Executive is This issue of Ausglass Magazine proceeding with preparations for the contains more technical information than Sydney conference and administering recent ones. This does not represent any the Association. The Executive is confident change of policy, but the practical is as that progress of the organisation will relevant to us as the aesthetic. So if continue and Linda envisages that she you have acontribution to make in this will still be able to help at committee area, don't hesitate. It is one of the level, albeit in a reduced capacity. many factors to balance in running Contact with the Executive can still be ajournal of this nature. made via the address on the contents Mark Brabham's page of this magazine. article on gas burners Gerie Hermans' piece on European is a long one, but is Glass '97 indicates that year will be an useful data for anyone exciting time in Holland. She may contemplating attend some of the events and has establishing gas promised to keep us informed. furnaces or kilns. Thanks for the positive feedback Let me know if you would like some regarding the new look magazine, it further backup information on this topic. has been remarkable. Without the help If you have other technical questions or of Chris Bohan and Tactix Design, it problems to solve, drop us aline and we would not have been possible. will endeavour to find answers. Ausglass Magazine now has an ISSN The excerpt from Henry Halem's (International Standard Serial Number) Glass Notes has been included for and can be traced internationally via similar reasons and deserves the National Library of Australia. consideration by those involved in If you have any queries regarding making their own glass. Also in this articles or images in the magazine, issue abrief review of Glass Notes for fax me at: those of you not familiar with its Cold Glass Access Workshop, contents. This year, Henry received the (613) or (03) 9329 2272. Ohio Arts Council Governor's Award for services to Kent State University and to Happy Christmas glass. Henry's front cover drawing stems everyone, see you from his visit to Australia earlier in the in 1996. year, when he became enamoured of Sidney Nolan's paintings and the Ned Kelly saga. The experience also alerted him to aspects of the Australian landscape, with its profound influence on our culture. • Ausglass I­ Mark Brabham o ::::a:: G. SBurners and Is La"-- s·". Contra Atmospheric (Venturi) Burners These are burners that operate This method of firing is the Flame safety systems for these on gas only_ The velocity of the gas cheapest in terms of equipment costs burners are usually the thermoelectric stream flowing through an orifice but is also the least economical. Special type that can be used with or without entrains atmospheric air for combustion attention must be paid to obtaining as aseparate pilot Durner. The pilot from aventuri throat. The resultant neutral (correct mixture of atmospheric burner can serve as a low-fire setting or mixture burns at aspecially designed air and gas) a flame as possible as as aslow heat rise in the initial drying tip, of which there is awide variety, either oxidising (more air then gas) or out stages. Mount the pilot and/or known as aflame retention head. reducing (less air) flames or atmospheres safety probe well away from the For glory hole, tank and pot furnaces, are not only costly in fuel usage but furnace back heat. It is always better atmospheric burners generally use can have detrimental effects on the and safer to purchase the burners LP gas at high pressure as the pressure glass production. Although some assembled and pre-tested with the of reticulated natural gas is usually too secondary air (air entrained around the appropriate controls. low to inspirate enough air to generate burner tip) is necessary for complete Automatic ignition and quick a hot, short flame with any forward combustion, try to keep it to a lockout safety systems are readily velocity. Atmospheric natural gas minimum by correctly sized burner available as an option for these burners. burners may be used on lower ports and flue outlets. It is possible temperature ovens or furnaces. to check the furnace conditions by Pre-mix Open There is adefinite ratio between restricting the flue exit and checking and Sealed Burners the burner port area and the venturi for slight reduction. This will indicate These are burners using a throat. Typically, depending on the the settings are close to perfect. machined mixing set and forced air furnace back pressure, gas pressure It is difficult to achieve sufficient from a blower or compressor. Open and burner head design, the venturi temperature in glory holes and higher burners use asuitable flame retention throat area is approximately 40 to 50 temperature furnaces with these burners. tip and the sealed type utilise an RI per cent of the total port area. The greatest limitation, due to the low castable tunnel or MP tip mounted into Mismatching will result in a decrease in mixture pressure produced, is the the furnace wall. Natural gas or LP gas mixture velocity resulting in inadequate volume of combustion products that may be used at low pressure as the burning or, at worst, flash back. can be introduced to the furnace forced air induces the gas and produces This can also be caused by constricting combustion area. Simply increasing the a blast-type flame. These burners are the flow; use a preheat pilot if a lower combustion space size will not achieve more efficient than atmospheric rate is required. results as losses will increase burners as greater control is available proportionally. Obviously there is a fine over the air and gas mix, a hotter flame balance. In some cases better results is produced and the sealed burner have been attained by using several requires no wasteful secondary air. smaller burners rather than asingle, The open burner will only need In some cases better results large burner. Smaller burners with secondary air for cooling purposes to have been attained by using smaller gas orifices and higher gas prolong the tip's life. Some operators have several smaller burners. pressure would develop higher mixture traded tip life for lower noise by sealing pressures allowing more combustion the tip in the furnace port with fibre. products into the space. Continued over... Ausglass .. The higher mixture pressures Nozzle-mix (NM) Burners Special Burner Types developed by this burner style enables These types of burners accomplish In recent years many specialised greater combustion volumes into the the mixing of the air and gas after they burners used in large industrial available furnace combustion space. leave the burner port. Up to the burner applications have become available Some careful preheating of the head the air and gas are kept separate, for glass working. combustion air is possible, although lower gas and air pressures may be used not recommended, as there is a risk of and there is no chance of flash back. Multipart Refractory Burners flashback or damage to the controls They generally have greater turn down through heat conduction. Although used in industry as than other burner types but the main Pre-mix burners generally have a radiant type burners for many years, advantage in glassworking is shorter flame length than comparable this multiport variation for glory holes recuperation. As the preheated nozzle mix burners, the air/gas ratio is was developed by the Swedish combustion air is kept separate there is easier to control and the burner overall company Essemce in conjunction with no chance of over-heating the gas generally easier to set up. Special flow Orrefors Glassworks with several controls. regulators can be fitted to simplify advantages in mind. The burner had to adjustment enabling alteration of air have a low noise level, be fuel efficient flow only to raise or lower the and reliable.