KEEP­ING COOL WITH FITZ­PATRICK VEN­TI­LA­TION

It goes with­out say­ing that for safety rea­sons, solid ven­ti­la­tion sys­tems need to be in place in min­ing en­vi­ron­ments, whether above or be­low the ground.

The Australian Mining Review - - FRONT PAGE - RAY CHAN

Ven­ti­la­tion is the con­trol of air move­ment, its amount, and di­rec­tion, and although it con­trib­utes noth­ing di­rectly to the pro­duc­tion phase of an op­er­a­tion, the lack of proper flow can cause lower worker ef­fi­ciency and de­creased pro­duc­tiv­ity, in­creased ac­ci­dent rates, and even ab­sen­teeism.

Air is nec­es­sary not only for breath­ing, but also to dis­perse the chemical and phys­i­cal con­tam­i­nants such as gases, dusts, heat, and hu­mid­ity.

Un­der­ground mine ven­ti­la­tion pro­vides a flow of air to the work­ings of a mine of suf­fi­cient vol­ume to di­lute and re­move dust and nox­ious gases (typ­i­cally ni­trous ox­ide, sulphur diox­ide, meth­ane, car­bon diox­ide and car­bon monox­ide) and to reg­u­late tem­per­a­ture.

The source of these gases are mainly the equip­ment that runs on diesel en­gines, the ex­plo­sives used for blast­ing, and the ore­body it­self.

In Aus­tralia, as well as in most of the world, mine ven­ti­la­tion prac­tice is heav­ily reg­u­lated, aimed at di­lut­ing fac­tors such as the diesel emis­sions, blast­ing fumes, ra­di­a­tion, dusts, bat­tery emis­sions, and many other con­tam­i­nants.

To en­sure ad­e­quate ven­ti­la­tion of a mine, pro­vi­sion is made for suit­able paths (air­ways or air cour­ses) for the air to flow down the mine to the work­ing places, and suit­able routes out of the mine when it has be­come un­suit­able for fur­ther use.

The pri­mary ven­ti­la­tion sys­tem thus con­sists of an in­take struc­ture through which the fresh air passes, the mine work­ings, and an ex­haust sys­tem where the air passes af­ter hav­ing ven­ti­lated the work­ing places of the mine. Mine fans are vi­tal to con­trol the air flow, and are in­stalled on in­take air­shafts, re­turn air­shafts, or both, ei­ther on the sur­face or un­der­ground.

FITZ­PATRICK EN­GI­NEER­ING

The largest com­po­nent of the op­er­at­ing cost for mine ven­ti­la­tion is elec­tric­ity to power the ven­ti­la­tion fans, which may ac­count for one third of a typ­i­cal un­der­ground mine’s en­tire elec­tri­cal power cost. So it’s es­sen­tial that when a min­ing com­pany builds fans at its sites, it gets value for money: it needs to en­sure the fans op­er­ate at max­i­mum ca­pac­ity suited to the work­ing con­di­tions of the re­spec­tive sites.

That’s where Fitz­patrick En­gi­neer­ing comes in.

Es­tab­lished in 1984, the Syd­ney-based com­pany has earned a world­wide rep­u­ta­tion for de­sign­ing and pro­duc­ing a wide range of qual­ity cen­trifu­gal and ax­ial flow fans, dampers and si­lencers for in­dus­trial, min­ing and min­er­als pro­cess­ing, both in Aus­tralia and over­seas.

Ac­cord­ing to com­pany spokesman Steve Tran, Fitz­patrick man­u­fac­tures fans rang­ing from small units weigh­ing around 100kg with a mo­tor power of just a few kW, to fans weigh­ing 20t with a ro­tat­ing im­peller mass of 4800kg.

TYPES OF FANS

The com­pany’s cen­trifu­gal fans use wheels nor­mally mounted in a fan or blower hous­ing.

The air en­ters the hous­ing in­let, turns 90° and is ex­hausted out of the hous­ing dis­charge. They’re all ro­bust, welded with steel sheets and plates and re­in­forced with an­gle iron frames.

Steve said the com­pany’s fans in­cluded mod­els with aero­foil, ra­dial tip, and back­wards-in­clined blades, all of which are suited to vary­ing oper­a­tions. “One could be a high mass flow fan, one could be a high pres­sure fan,” he said. “They are used in dif­fer­ent ap­pli­ca­tions, depend­ing on what the cus­tomer re­quire­ments are. “For min­ing specs, the sites usu­ally in­volve mov­ing large vol­umes of air, but we’re not lim­ited to one in­dus­try or the other. “We can do just one mas­sive fan, or ra­dial and back­wards in­clined blade fans that can move large vol­umes of air.”

MA­TE­RIAL HAN­DLING IMPELLERS These fans have straight ra­dial blades with open impellers ar­ranged like a pad­dle wheel, mostly used in ma­te­ri­al­shan­dling oper­a­tions. Eight de­signs cover high to very low flow rates, in­clud­ing the RM se­ries high flow rate stan­dard units for 5kPa, the RMB high flow rate with back­plate for han­dling stringy ma­te­rial, and the MH se­ries for low to very flow rates.

RA­DIAL-TIPPED BLADE AND RA­DIAL BLADE FANS

Also termed curved blade fans, Steve said ra­dial-tipped blade fans are used in mod­er­ate-vol­ume flow rate ap­pli­ca­tions when the pres­sure re­quire­ment is mod­er­ately high and ero­sion re­sis­tance is prefer­able. This de­sign re­duces the po­ten­tial for dust build-up on the un­der­side of the blades in ap­pli­ca­tions with medium amounts of gas-borne dust.

“It of­fers higher pres­sure and more com­pact de­sign than aero­foil and back­ward-in­clined impellers in ex­change for lesser ef­fi­cien­cies and in­creased power de­mand,” Steve said. These rugged fans of­fer high pres­sure ca­pa­bil­ity with av­er­age ef­fi­ciency, and are of­ten fit­ted with ero­sion-re­sis­tant lin­ers to ex­tend ro­tor life.

They’re gen­er­ally used when high quan­ti­ties of abra­sive dust are present in the gas stream, or when very high gas tem­per­a­tures are ex­pected. The ra­dial tip se­ries mod­els that Fitz­patrick man­u­fac­tures are ap­pli­ca­ble for a range of high flow rate pres­sures up to 12kPa or low flow rate pres­sure up to 20kPa

BACKWARDLY IN­CLINED AERO­FOIL BLADE AND PLATE FANS

Aero­foil impellers pro­vide uni­form, high vol­ume air­flow with low power con­sump­tion for op­ti­mum ef­fi­ciency us­ing the same aero­dy­nam­ics that cre­ate flight.

As air ap­proaches the blade’s lead­ing edge, the stream splits and trav­els above and be­low the blade.

It is then de­flected across the con­vex curve along the top of the blade and along the flat or con­cave curve on the bot­tom, flow­ing down­ward over the sharp trail­ing edge as it leaves the blade.

The lift de­vel­oped from the blade is a con­tribut­ing fac­tor to re­duc­ing power con­sump­tion as it ro­tates which is why it has the high­est ef­fi­ciency com­pared to other cen­trifu­gal fan de­signs. “Aero­foil fans are the most com­monly used to move large vol­umes of air,” Steve said. “At higher flow rates, they be­come more ef­fi­cient com­pared to other types of blades.”

As the fan ro­tates a pres­sure dif­fer­ence is cre­ated on the im­peller blades. On the lead­ing, con­vex side of the im­peller blade, a pos­i­tive pres­sure is cre­ated as the ro­ta­tional mo­tion of the im­peller im­parts a force in the air. The blade pushes the air out­wards, ex­it­ing in a ra­dial di­rec­tion. On the con­cave side of the im­peller blade, a neg­a­tive pres­sure is cre­ated as the fan ro­tates, draw­ing air into the space be­tween the blades.

This air is then picked up by the fol­low­ing blade and forced out­wards ra­di­ally in a con­tin­u­ous process. The suc­tion side of the im­peller blade draws air from the cen­tre of the fan which re­sults in a di­rec­tional change of the air­flow be­tween the in­let and the ex­haust of 90°.

Steve said these fans were used ex­ten­sively for con­tin­u­ous ser­vice at am­bi­ent and el­e­vated tem­per­a­tures in forced and in­duced draft ap­pli­ca­tions in the met­als, chemical, power gen­er­a­tion, re­source re­cov­ery, in­cin­er­a­tion and other in­dus­tries through­out the world.

The backwardly-in­clined plate blade fans, mean­while, are de­signed to han­dle large vol­umes of rel­a­tively clean air, com­monly used for in­dus­trial air sup­ply and ex­haust ap­pli­ca­tions. Fitz­patrick En­gi­neer­ing en­sures they are con­structed heav­ily with hard­ened al­loy steel plate. They have a per­for­mance air flow of 344,300 CFM (584,965 m3/hour), and are ca­pa­ble of cop­ing with non-sticky abra­sive dust loads.

This de­sign is a cost-ef­fec­tive al­ter­na­tive to the aero­foil de­sign, but with flat plate blades in­stead of curved, re­sult­ing in a slightly lower ef­fi­ciency, com­pen­sated by the eas­ier fit­ting of lin­ers and man­u­fac­tur­ing process.

FITZ­PATRICK IS IN THE HOUSE

Steve said that the com­pany is 100pc Aus­tralian-owned and car­ries out all de­sign, de­vel­op­ment and man­u­fac­tur­ing of its prod­ucts in Aus­tralia. “All the fab­ri­ca­tion is done in-house, in­clud­ing rolling, press­ing, weld­ing, as well as the ma­chin­ing and paint­ing,” he said. “This gives us the flex­i­bil­ity and ca­pa­bil­ity to take on cus­tom projects within the air build­ing fan in­dus­try or out­side.

“Also, this means that if there’s a shut­down or emer­gency, we have room to al­low for that sort of work.” The com­pany boasts around 40 stan­dard aero­dy­namic fan de­signs, with the list con­tin­u­ing to grow as it de­vel­ops new de­signs or adds fur­ther op­tions to ex­ist­ing de­signs to en­hance their per­for­mance and ver­sa­til­ity.

The work­shop has two ar­eas of op­er­a­tion: steel fab­ri­ca­tion and ma­chin­ing, and de­sign and man­u­fac­ture. Both com­bine to im­prove the abil­ity to re­duce pro­duc­tion cost and al­low the man­u­fac­tur­ing process to run more smoothly and ef­fec­tively. “Ex­e­cut­ing these two ar­eas un­der one roof has re­sulted in much quicker turn­around,” Steve said. Qual­i­fied engi­neers are em­ployed to en­sure cus­tomers choose the right fan for their ap­pli­ca­tion with min­i­mum sup­ply lead time and best-in-class per­for­mance.

The cen­trifu­gal fans are en­gi­neered to op­er­ate with high aero­dy­namic ef­fi­ciency, smooth run­ning low vi­bra­tion/noise lev­els and a com­pact, low pro­file foot­print.

All Fitz­patrick prod­ucts are man­u­fac­tured within an ISO 9002 qual­ity con­trol sys­tem, air­flow and sound-tested in DIN 45635 cham­bers, and bal­anced to ISO 1940 stan­dard G2.5 and G6.3 where re­quired. The com­pany ac­knowl­edges that the cus­tomer is king, and can man­u­fac­ture units to the clients’ wishes.

“If a 1m di­am­e­ter blade fan is not suf­fi­cient, we can scale up to 2m,” Steve said. “Gen­er­ally though, the big­ger the blade, the less you need to run the speed, for safety rea­sons. “For ex­am­ple, you can run a 1m fan up to 3000rpm … but us­ing some­thing big­ger, some­thing that fast, is ask­ing for a dis­as­ter.

”For some­thing around 2m, we might go up to 1000 rpm; it’s cer­tainly some­thing we take into con­sid­er­a­tion in the cal­cu­la­tions.”

In­deed, when it comes to gaug­ing per­for­mance, the com­pany pro­vides per­for­mance graphs to clients for each model which de­picts their abil­ity to push at cer­tain flows at par­tic­u­lar pres­sures.

“We match fan re­quire­ments with the mod­els to make se­lec­tion eas­ier,” Steve said. The com­pany also in­cor­po­rates some spe­cial fea­tures into their fans. “We in­cor­po­rate the ef­fects of the op­er­at­ing en­vi­ron­ments into the build,” Steve said. “For ex­am­ple, we en­sure our un­der­ground fans are ex­plo­sion­proof rated.

“We use brass cages around whole com­po­nents and mov­ing parts to avoid steel-on-steel con­tact. “We are aware that any spark or gas leak could lead to a catas­tro­phe, so we make sure the fans are cer­ti­fied, min­ing-spec ap­proved and made of anti-spark­ing ma­te­rial.”

The com­pany can equip EXD elec­tric mo­tors for the fans, which are specif­i­cally made to be ex­plo­sion-proof and are used widely at min­ing sites and other haz­ardous ar­eas. “Mo­tors range in size from small to huge, from 7.5kw to 1000kw, which of course would move a large amount of air,” Steve said.

GLOBAL FOL­LOW­ING

Fitz­patrick En­gi­neer­ing is proud to claim that it is one of the coun­try’s lead­ing man­u­fac­tur­ers of high qual­ity in-house in­dus­trial fans, backed by qual­i­fied engi­neers with ex­ten­sive ex­pe­ri­ence in lead­ing tech­nol­ogy in­no­va­tion. It boasts ro­bust en­gi­neer­ing re­li­a­bil­ity, qual­ity sys­tems, and sup­plies prod­ucts to any­where in the world.

With that sort of un­com­pro­mis­ing qual­ity and wide sup­port from var­i­ous re­source sec­tors, you might even say that there are lit­er­ally many, many fans of this com­pany’s many, many fans.

A CAD model of a 2300mm ax­ial fan.

A si­lencer unit used for fan sound sup­pres­sion. 60 se­ries ra­dial tip fans have straight ra­dial blades and are used on ap­pli­ca­tions where dust or ma­te­rial has to pass through the fan. Straight ra­dial blade ma­te­ri­als han­dling fans are the most re­sis­tant to ma­te­rial build-up of any cen­trifu­gal fan type. All of these fans are de­signed for lower flow rates.

54 se­ries aero­foil blade fans, which are de­signed for high flow rates, with pres­sures to 12 kPa. The ver­sa­tile de­sign can be used for both di­rect drive and vee belt drive ap­pli­ca­tions for mov­ing clean air and light non-sticky dust loads. 55 se­ries back­ward-in­clined plate blade fans, which in­cor­po­rate high flow rate stan­dard de­signs to 5 kPa. The backwardly in­clined plate blade fan is de­signed to han­dle large vol­umes of rel­a­tively clean air, com­monly used for in­dus­trial air sup­ply and ex­haust ap­pli­ca­tions.

The model 6360 curved plate fan, which of­fers low flow rate pres­sures to 18 kPa.

A fan per­for­mance guide for ax­ial fans, show­ing the ef­fects of fan to­tal pres­sure on vol­ume flow rate.

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