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H2 SERIESHydrogen Control Panels and Safety Systems for Alloy Retort FurnacesAPPLICATIONSThe H2 Series Flow Control System isdesigned for introducing and controllinghydrogen in a closed retort batch furnace likethe XLC and JSC Series. The safety systemexceed the NFPA-86C (National Fire ProtectionAssociation) standards for controlledatmosphere furnaces. With this system hydrogenmay be introduced into a furnaceretort at any temperature. Hydrogen is usedfor bright annealing of stainless steel andcopper alloys, chemical reductions, magneticsteels, coatings, brazing and many otherprocesses. Flow rates and ranges areengineered for specific systems althoughtypical flow rates are three to ten volumechanges per hour.FEATURESATMOSPHERE FLOW CONTROLThere are three separate flow systems, onefor hydrogen, one for purge gas and one foremergency purge. All three lines includeseparate shut off valve, pressure regulator,relief valve, pressure gauge, solenoid forautomatic shut off, flowmeter with regulatingvalve and check valve. In addition thehydrogen line includes a low flow switchwhich will shut off hydrogen if flow is notsufficient to maintain positive retort pressure.A delay timer temporarily bypasses theswitch for hydrogen introduction. A flamearrestor is also on the hydrogen line. The twopurge lines include pressure switches tomonitor the ability of the purge gas to flow incase of an alarm condition. Low pressureopens solenoids from both lines. Purge gasmay be nitrogen, argon or helium - althoughargon needs special engineering to workproperly. A totally separate emergency inertgas purge line includes a normally opensolenoid for automatic actuation. Emergencypurge is activated in case of a power failure.INERT PURGE IN ELEMENT CHAMBERThe furnace has a separate inert atmospherepurge between the outside of the retort andthe elements. This has its own flowmeterwith regulating valve and branches off theinert process gas purge. This protects thesystem in case of a leak in the retort. It isespecially important when operating withhydrogen below 1400°F (760°C). A low flowswitch will initiate emergency purge if there isa low flow of purge gas around the retort.Page 16ELECTRIC BURN OFF IGNITORAn electric ignitor maintains a positiveignition source at the gas exit. The systemsignals an alarm to shut off hydrogen if theignition source is lost.WATER COOLING SYSTEM & ALARMOn retorts that have water cooled seals amanual ball valve shut off, flowmeter andregulating valve, relief valve and low flowswitch are included plus hook ups for theinlet and outlet. The low flow alarm turns offelement power and hydrogen flow and theninitiates a purge. Self-contained circulatingwater cooling systems are also available.VISUAL AND AUDIBLE ALARMSAn audible buzzer with silencer is provided toindicate any alarm condition. In addition,control indicators or pilot lights indicateprecisely which alarm conditions areactivated and what gasses are flowing. Thesilencer does not turn off indicators.PURGED CONTROL PANELThe main electrical control panel is purgedwith instrument air or nitrogen. A differentialswitch must be activated for the controlsystem to operate. All electrical componentsthat are in the hydrogen flow area are eitherexplosion proof, intrinsically safe or renderedsafe per N.E.C. (National Electrical Code)articles 500 and 501.LOW TEMPERATURE ALARMA temperature based alarm can be set at anytemperature (normally 1400°F / 760°C) belowwhich hydrogen shuts off. This is not strictlynecessary when using the purge in, purge outmethod of hydrogen introduction or removal;however, it is an extra level of safety that canbe used when desired.LOSS OF EXHAUST VENTILATIONA differential pressure switch installed in theventilation system initiates purge and shuts offall power in the case of low ventilation flow.SAFETY REGULATIONSThis atmosphere system meets or exceedsthe standards of the National Fire ProtectionAgency for controlled atmosphere furnaces(NFPA-86C). L&L will provide all necessaryinformation to customer’s insurance carrieror other authorities for approval purposes.ATMOSPHERE INSTRUCTIONSA very complete instruction manual includestheory of operation, full maintenanceinstructions and schedules, component lists,component instructions, data sheets, emergencyprocedures, cautions, start up and shutdown procedures and a complete flowschematic of the atmosphere system.INTRODUCTION OF HYDROGENThe hydrogen must be introduced into thefurnace manually by activating a switch on thecontrol panel. This is according to theNFPA-86C standards. An automatic purgecycle with automatic introduction ofhydrogen is not allowed. Using the “purge in”method the operator must twice confirmthat the oxygen content inside the furnace isbelow 1% before introducing hydrogen.OTHER GASSES AND PANELSOther gasses such as ammonia, carbondioxide, carbon monoxide, oxygen, etc. can beintegrated into the gas mixing panel withappropriate safety systems. In addition wemake nitrogen/methanol panels (see page 30)and nitrogen/propane or natural gas panels(see page 6). We only make atmospherepanels for our own furnaces.OPTIONS● OXYGEN/HYDROGEN ANALYZER: Nova340 Portable combination oxygen and hydrogenanalyzer is commonly supplied. This meets the NFPArequirements for gas analysis when doing the purgein, purge out method of hydrogen introduction andremoval. Includes power supply and pump.● DELTA F OXYGEN ANALYZER: Model PA31525 A-Plus. An alarm prevents hydrogen fromflowing and initiating a nitrogen purge at any timeif oxygen level rises above 1%.● HYDROGEN LEAK MONITOR: Monitorsroom air. Calibrated for 1/4 of the LEL (1%hydrogen). An alarm output from this sensor shutsoff hydrogen and activates audible alarm.● BUBBLER FOR WET HYDROGEN: A manualor event driven bypass allows the hydrogen to bepiped through a bubbler to make wet hydrogen.Automatic PID control is also optional.● MASS FLOWMETERS: One or more of theatmosphere lines can have a mass flowmeter tocontrol the flow rates very precisely. This can berecorded with an output to a datalogger.● HYDROGEN HIGH FLOW SWITCH: A highflow switch shall initiate purge when 150% ofprocess requirements are exceeded.● STAINLESS PIPING FOR HYDROGEN: Allflow components in the hydrogen line and allpiping and fittings can be made of stainless steel.Compression fittings or all welded connections canbe used. Also piping and components can becleaned for oxygen service.● INSTRUMENT AIR FILTERS FOR PANELPURGE: Two special Balston filters convertcompressed air into instrument quality air for thepanel purge.● START UP & TRAINING SERVICE: Two tothree days is typical.www.hotfurnace.com