Used Vei Gas-Fired Continuous Furnace for sale (10,273)

Condition: used, Year of construction: 2015, operating hours: 19,600 h, functionality: fully functional, fuel type: gas, power: 2,028 kW (2,757.31 HP), output voltage: 400 V, output frequency: 50 Hz, rotational speed (max.): 1,500 rpm, motor manufacturer: MTU, =Scope of supply= Complete set of 3 x MTU 16V4000 GS (16V4000L64) with Skid cooling groups Radiators Ibsdjzmnzaopfx Agyoc Absorption chiller Genset outgoing breakers Lube oil systems Electrical auixiliaries panels MTU - MCS , MTU - MMC panels =Technical specifications= Time for delivery - in stock Engine type - 16V4000L64 Electrical power - 2028 kW Engine speed - 1500 rpm Total efficiency - 89 % Voltage - 400 V Frequency - 50 Hz =Other information= Production country - Germany

Condition: excellent (used), Year of construction: 2022, operating hours: 600 h, functionality: fully functional, machine/vehicle number: PO210417, total width: 4,600 mm, total length: 25,000 mm, total height: 3,000 mm, type of input current: three-phase, energy consumption: 1,700 kWh, input current: 2,230 A, The AG series of convection tempering furnaces with forced air circulation (Northglass fifth-generation furnaces, featuring proprietary focused convection technology) was developed to meet the growing customer demand for more efficient low-E glass tempering, improved product quality, and reduced energy consumption. The AG series furnace integrates the advantages of a four-convection furnace, primarily offering benefits in terms of higher productivity, superior product quality, and easier process control. The furnace consists of loading conveyors, a heating section, a convection system (upper and lower), a flat tempering/cooling section, and an unloading conveyor. The equipment package includes air ducts and a device control system. Max. working width: 2,850 mm. Max. loading length: 5,000 mm. Max. glass loading area: 2,850 x 5,000 mm (5-19 mm), 2,850 x 4,600 mm (4 mm). Upper fan convection: 6 fans x 4 kW, lower: 6 fans x 3 kW. Main technical data is attached in a PDF file. Iodpfx Aez Dhm Uegyjbc

Condition: excellent (used), Year of construction: 1993, fuel type: electric, height 2300 mm Iedpfx Agez Dkz Ieyebc length 3200 mm total wight 7300 kg height of stroke 5175 mm weight max. 5 t weight 7300 kg

Condition: excellent (used), Year of construction: 2008, functionality: fully functional, workpiece weight (max.): 800 kg, We are offering this very well-maintained Balzer 800 aluminum melting furnace, manufactured in 2008. Manufacturer: Balzer Model: Balzer 800 Ibjdpfx Ajz Dpy Njgysc Year of manufacture: 2008 Condition: very good Category ID: 235 Type ID: 1729 Machine type: Aluminum melting furnace If you have any questions or require further information, please feel free to send us a message or call us.

Condition: used, Year of construction: 2021, functionality: fully functional, Dürr Ecopure VAR 2206 Thermal Oxidizer with Flue Gas Cleaning (2021) For burning liquid and gaseous waste streams including fluorinated gases, e.g. PFAS, and recovery of aqueous hydrogen fluoride Emissions limits SO2 ≤ 100 mg/Nm³ NOX ≤ 30 mg/Nm³ CO ≤ 50 mg/Nm³ CF4 ≤ 70 mg/Nm³ HF ≤ 1 mg/Nm³ NH3 ≤ 2 mg/Nm³ Comprising Direct fired thermal oxidizer Hot gas cooling and acid recovery Alkaline wet scrubber Honeycomb selective catalytic reduction deNOx system >1M cost spare parts Direct fired thermal oxidizer Including 2x natural gas combustion chambers and burners - High calorific liquid waste requires safe ignition supplemental hydrogen supply for acid formation - Gaseous waste streams injected via nozzles downstream and close to the burner - 1.5MW multi-fuel natural gas & liquid waste (minor fuel stream) burner with natural gas capacity up to 200Nm3/h - 1400C normal, 1540C max allowable temperature destruction of pollutants to reduce emissions with 3.28 MW thermal energy transfer - 2 seconds minimum residence time in combustion chamber at 1400C - 1,800mm combustion chamber internal dia. - Approx 300mm refractory lining - 2,400mm combustion chamber external dia. - 12,000mm combustion chamber internal length - 3.28MW maximum thermal capacity - 4,900Nm3/h, 60mbar, 14kW combustion air fans One chamber is active, the other one is on standby and can be prepared, repaired, or maintained. This allows minimizing shutdown and changeover time to only several days Wet scrubber hot gas cooling and acid recovery SGL Carbon Diabon HT-PQ 850 graphite pipe quencher - 6,000 Nm3/h capacity flow - 1,100 mm dia. - 2,000mm high - pumps SGL Carbon Diabon THX-RS falling film absorber shell & tube heat exchanger - 1,100mm dia. - 4,500mm tube length - 595 no. tubes - 22mm tube internal dia. - Graphite, carbon steel - pumps Quench vessel - PP/FRP - 1,100mm dia. - Approx. 6,000mm high 2x Scrubber absorber columns, each - Shell FRP/PP - Internals PP - 1,000mm dia. - 11,000mm high - Pumps - Dosing station FRP 5m3 Emergency water tank - 1,600mm dia. - 3,000mm high - 3kW heating 2x Teblick 100,000L HDPE hydrofluoric acid tanks (2019) Honeycomb selective catalytic reduction deNOx system - 5,900Nm3/h, 130mbar, 42kW induced draft fan - 320 kW gas/gas heat exchanger - 500 kW capacity reheat burner - 1.2m deNOx honeycomb catalyst Clean gas outflow Stack with flow & temperature measurement Spare parts include - 200 items of sensors, pumps, valves, gaskets, joints etc. - Graphite quencher - Falling film absorber With the redesign and maintenance support of Dürr, the system could also Ijdpfxjz Ai Tps Agyobc - be adapted to other halogenated gases with bricks to be selected according to gas application - cope with the presence of VOCs or contaminated air - larger volumes with the addition of a small lance for 15kg/h liquid injection

Condition: ready for operation (used), functionality: fully functional, machine/vehicle number: 30389, Year of construction: 2003, operating hours: 7,155 h, load capacity: 4,000 kg, lifting height: 3,990 mm, free lift: 1,100 mm, fuel type: gas, mast type: triplex, fork length: 1,800 mm, No minimum price – guaranteed sale to the highest bidder! TECHNICAL DETAILS Lifting capacity: 4,000 kg Lifting height: 3,990 mm Free lift: 1,100 mm Ibodpfoz Eaffjx Agyoc Fork length: 1,800 mm Minimum fork width: 250 mm Maximum fork width: 1,160 mm Number of wheels: 4 MACHINE DETAILS Mast type: Triplex Fuel type: Liquefied petroleum gas (LPG) Engine manufacturer: Toyota Operating hours: 7,155 h Dimensions & Weight Dimensions (L x W x H): 3,130 x 1,420 x 2,270 mm Unladen weight: 6,720 kg EQUIPMENT Side shift Documentation CE marking

Condition: ready for operation (used), functionality: fully functional, machine/vehicle number: H21202Y06382, Year of construction: 2021, operating hours: 10,037 h, load capacity: 3,000 kg, lifting height: 4,495 mm, fuel type: gas, mast type: simplex, construction height: 2,925 mm, No minimum price – guaranteed sale to the highest bidder! TECHNICAL DETAILS Load capacity: 3,000 kg Lifting height: 4,495 mm ISO class: 3 Load capacity class ISO: 2,500–4,999 kg MACHINE DETAILS Iodez Dw Ubjpfx Agyobc Mast type: Simplex Fuel type: Gas Overall height: 2,925 mm EQUIPMENT 3rd valve 4th valve Heater Full cabin

Condition: ready for operation (used), functionality: fully functional, machine/vehicle number: H2X393X00765, Year of construction: 2020, operating hours: 9,763 h, load capacity: 3,000 kg, lifting height: 4,350 mm, fuel type: gas, mast type: simplex, construction height: 2,914 mm, No minimum price – guaranteed sale to the highest bidder! TECHNICAL DETAILS Load capacity: 3,000 kg Lifting height: 4,350 mm ISO class: 3 Load capacity range, ISO class 3: 2,500–4,999 kg MACHINE DETAILS Mast type: Simplex Fuel type: Gas Overall height: 2,914 mm EQUIPMENT 3rd valve Ibjdpfx Aez Dw Uzegysc 4th valve Heater Full cabin Air conditioning

Condition: used, mileage: 2,14,050 km, power: 96 kW (130.52 HP), first registration: 06/2020, fuel type: diesel, overall weight: 3,400 kg, color: yellow, gearing type: automatic, emission class: euro6, number of seats: 3, total length: 5,340 mm, total width: 1,986 mm, total height: 1,956 mm, Equipment: ABS, air conditioning, central locking, electronic stability program (ESP), parking heater, soot filter, Internal vehicle number: 4129BX ----Why Autonext? Over 400 immediately available cars and commercial vehicles. One of the largest vehicle showrooms in the region. Over 1,000 satisfied customers annually - top customer ratings. Attractive financing and trade-in options available. The entire vehicle range can be found at: autonext? Mobility made easy. WhatsApp Chat: ### Offer: Financing from 4.99% ### ----Good and well-maintained condition! 1st owner, German vehicle, non-smoking vehicle *Complete service history exclusively at Ford* New front and rear brakes New all-season tires on the rear Ambulance/patient transport vehicle Wheelchair-accessible conversion Wheelchair ramp Stretcher securing system O² cylinder holder incl. connection Flashing lights & siren Pre-equipment for radio incl. radio antenna Automatic transmission Rearview camera Auxiliary heating 2x air conditioning 230V socket Inverter Trailer hitch on request ---- Special equipment: * Ford SYNC 3 * Audio/radio remote control on the steering wheel * Radio preparation, 6 speakers * Touchscreen color display (8 inches) * Visibility Package 3 * Exterior mirrors, electrically foldable * Exterior mirrors, electrically adjustable and heated Iedpfex Tmwpex Agysbc * Headlight assistant with day/night sensor * Driver assistance system: High beam assistant (headlights with automatic dimming) * Windshield wiper with rain sensor * Heated windshield * Driver assistance system: Lane keeping assist with drowsiness detection sensor * Adaptive cruise control (cruise control) with distance control ACC * Driver assistance system: Emergency braking assistant * Driver assistance system: Collision warning system * Driver assistance system: Traffic sign recognition system * Seat Package 14: Driver's seat (4-way adjustable) - Front passenger single seat (4-way adjustable) incl. seat heating, fabric * Seats in the cab: Driver's seat heated * Seats in the cab: Front passenger seat heated * Seats in the cab: Front passenger single seat * Seats in the cab: Driver's seat with lumbar support * Rear window tinted (privacy glass) * Rear window heavily tinted * Deletion of 3rd row of seats in the cargo/passenger compartment * Driver assistance system: Lane change warning system * Windows in the cargo/passenger compartment: - can be opened * Generator 240 A * Configuration with specific central locking * Fleece battery 80 Ah (AGM, 2 batteries) * Thermal protection glazing cargo/passenger compartment, medium tint Standard equipment: Windows in the cargo/passenger compartment: - fixed, 2nd row left, Windows in the cargo/passenger compartment: - sliding, 2nd row left, Cornering light in the headlight, Storage compartment in the headliner of the cab, Airbag passenger side, Airbag driver side, Active cornering light, Anti-lock braking system (ABS), Anti-slip control (ASR), Drive type: Front-wheel drive, Exterior mirrors electrically adjustable and heated, Turn signal integrated in the exterior mirror, Floor covering: Rubber in the cargo/passenger compartment (complete), On-board computer, Headliner in the passenger compartment, Entry lights, Electronic brake-force distribution (EBD), Electronic stability program (ESP), Electronic traction control, Driver assistance system: Hill start assist, Driver assistance system: Emergency braking assistant, Driver assistance system: Crosswind assist, Windows in the cargo/passenger compartment: - fixed, 2nd row right, Windows in the cargo/passenger compartment: - fixed, 3rd row left, Windows in th

Year of construction: 2025, condition: like new (used), Nu-Way Enertech FMP40-MOD-NG350P+ Gas Burner Ibsdpfx Agsz E Nnpjyec 2025, unused, compact industrial packaged gas burner, covers outputs up to 150 therms, NAT GAS, 1.1Kw motor, 3Ph

Condition: reconditioned (used), We manufacture the original. We offer you a used, workshop-reconditioned granulator GA75 / 9 for sale. - Motor power: 75 kW, new motor Ibedeh S U Ryjpfx Agyec - 9 rows of rotor knives, 4 stator knives - new rotor with completely new bearings and new, hardened wear parts. Inquiries only from commercial businesses!

Condition: used, Cryogenic gas tank semi-trailer CRYOBASE used for liquid oxygen, nitrogen and argon Ibedpfx Asznb Nyjgyjc Capacity: 24 m³ Date of first registration: 29.09.2025 Pump, flow meter, vaporizer, vacuum insulation. New technical inspection (HU), vacuum and leak test. We also have other tankers for LIN, LOX, LAR, LNG and CO2, argon, oxygen, nitrogen and carbon dioxide, LNG, Hydrogen, Methane. We will be glad to answer your questions via Phone and E-mail

Condition: used, fuel type: diesel, axle configuration: 4x4, fuel: diesel, gearing type: automatic, Year of construction: 2004, From our immediately available stock of used vehicles, we offer you: Firefighting vehicle HLF 20 ALL-WHEEL DRIVE 4x4 on MB ATEGO 1328 AF General data: • First registration 03/2004 • Mileage: approx. 144,500 km • Unladen weight: 9,450 kg • Permissible total weight: 14,500 kg • New TÜV/MOT inspection Chassis: • MB 1328 AF 4x4 with 279 hp (205 kW) • Allison automatic transmission • Twin-tire rear axle Cabin: • Standard crew cabin (1:8) in RAL 3000 (fire engine red) • Mounting points for 2 compressed air breathing apparatus facing forward Superstructure: • Manufacturer: Schlingmann • HLF20 superstructure according to DIN standard • Three generously sized side equipment compartments on each side • Fold-out steps for the front and rear side equipment compartments • Mounting points for standard equipment • Mounting points for 2 additional compressed air breathing apparatus • Deployment system for 2 single-person reels Vehicle pump/fire extinguishing agent tank: • Firefighting centrifugal pump Schlingmann FPN 2000-10 • Output: 2,000 l/min at 10 bar • Water tank: 1,800 l • Foam tank: 150 l Firefighting equipment: • Fixed quick-attack hose, 50 m long, located on top • Monitor on the vehicle roof Safety and lighting • Ambient lighting on the superstructure • Pneumatic lighting mast • Rear warning device We will gladly provide you with a detailed offer and show you the vehicle in Berlin. Ibodpjzv Eqkofx Agyoc All information is provided to the best of our knowledge and belief, without guarantee for completeness and accuracy. This advertisement does not constitute an offer, but rather information. Subject to prior sale!

Condition: good (used), Year of construction: 1973, rust size: 700 x 650 x 1.100 mm batch weight: 1.000 kg Temperature: Max. 750 °C Iodezvfdqspfx Agysbc connected load: 78 kW Equipment: Incl. Control system (should be renewed) + Charging machine others: Furnace can be moved under nitrogen

Condition: excellent (used), Year of construction: 2002, Consisting of: - 2 pieces hardening furnaces 10 Cg gross weight 400 kg - 1 piece of nitriding oven 8 Cg gross weight 400 kg - 1 piece spray washing machine Ibodpfxjzvfluj Agysc - 2 pieces tempering furnaces - 1 piece of oil quench bath 5000 liters - 1 piece manipulator All technical data for the individual systems can be found in the attached pictures.

Year of construction: 2016, condition: used, An automatic oven loading system for rack ovens is offered. Equipped with a multi-level loading carrier, protective enclosure and movable loading unit. Inspection possible by appointment. Ibsdpfx Agjz H Uttsysc

Condition: excellent (used), Year of construction: 1996, CRYOLOR gas tank semi trailer for oxygen, nitrogen, argon cryogenic Ibodpfx Asu Uni Sogysc Year: 1996 We also have other tankers, tanks, vessels for LIN, LOX, LAR, LNG and CO2, argon, oxygen, nitrogen and carbon dioxide, LNG, Hydrogen, Methane We will be glad to answer your questions via Phone and E-mail

Condition: used, Manufacturer: DEMAK Housing size: 6600 x 2100 mm Maximum temperature: 200 °C In the past, the oven was part of a plant and the product was transported via a conveyor belt, Iodpjvgy Ivsfx Agyebc The oven was previously controlled by PLC, it was dismantled,

Condition: used, mileage: 62,506 km, power: 117 kW (159.08 HP), first registration: 09/1971, fuel type: diesel, empty load weight: 8,020 kg, maximum load weight: 3,580 kg, overall weight: 11,600 kg, tire size: 8,25-20 PR 12, axle configuration: 4x2, wheelbase: 4,200 mm, color: red, driver cabin: other, gearing type: mechanical, suspension: steel, number of seats: 6, total length: 7,000 mm, total width: 2,450 mm, total height: 2,650 mm, Vehicle location: Bovenden, switch 5, rotating beacon, leaf suspension Wheelbase: 4200 mm Superstructure: Gebr. Bachert TRO-TLF16 approx. 2000 ltr. 6-cylinder fire-fighting vehicle, a Bachert FP16/8 centrifugal fire-fighting pump with a water delivery rate of 1600 l/min at 80 mWS total delivery head is installed in the rear of the vehicle. With H-approval. ACCESSORY INFORMATION WITHOUT WARRANTY, subject to alterations, prior sale and errors excepted! Iodsvhhgpspfx Agyjbc - .

Condition: excellent (used), Year of construction: 1996, Gas, compressed helium, hydrogen, Wasserstoff, 196 bar semi trailer Manufacturer: Fruehauf year: 1996 Tare: 26480 kg Total weight: 30630 kg Tank Volume: 16,5 m3 Working pressure: 196 bar Ibsdpfxsvvivzo Agyoc We also have other tankers for LIN, LOX, LAR, LNG and CO2, argon, oxygen, nitrogen and carbon dioxide, LNG, Hydrogen, Methane We will be glad to answer your questions via Phone and E-mail

Condition: new, Year of construction: 2025, Fully automatic continuous side sealer for fast and reliable product flow due to continuous motion sealing unit. PRO-Version including external infeed belt and side guide rails for products in multi-pack format. Different guide rail systems are available depending on product height and shape. Touchscreen panel for user friendly operation. No-product-automatic-stop-system. Easy and fast changeover of formats. Less film wastage reduces film costs. Ideal in combination with the AMTEC SHRINKtunnel POF-L (High-Speed) PRO-Version. Can be combined with POF-PE-Shrink Tunnel. - Specifications: max. speed of the machine in neutral: 70 cycles/minute; max. packaging size: L(80-700)xW(80-380)xH(10-180) mm; sealing blade length: 530 mm; 220V, 5 kW, 6bar, 0.6m³; machine dimensions: L4100xW1610xH1370 mm. Ibodpfx Agev Nl Hcsysc Please note that our new prices are often below the usual used prices. Please feel free to inquire and tell us your packaging task. - Usually 30-50 different new machines are available immediately from stock. In addition, we have very short delivery times from approx. 3 weeks for customized machines. Deviations from the sample photo are possible. - All machines are available with full warranty.

Condition: new, Year of construction: 2025, Fully automatic High-speed Sideshrink Machine. Continuous motion sealing machine with moving sealing unit for reliable and trouble free packaging. PRO-Version including external finger chain infeed conveyor system and friction feeder. Touchscreen panel for user friendly operation. No-product-automatic-stop-system. Easy and fast changeover of formats. Less film wastage reduces film costs. Ideal in combination with the AMTEC SHRINKtunnel POF-L (High-Speed) PRO-Version. Can be combined with POF-PE-Shrink Tunnel. - Specifications: max. speed of the machine in neutral: 120 cycles/minute; max. packaging size: L(80-1000)xW(80-400)xH(5-180) mm; sealing blade length: 500mm; 220V, 6.5kW, 6bar, 0.6m³; machine dimensions: L5405xW1780xH1380 mm. Please note that our new prices are often below the usual used prices. Please feel free to inquire and tell us your packaging task. - Usually 30-50 different new machines are available immediately from stock. In addition, we have very short delivery times from approx. 3 weeks for customized machines. Deviations from the sample photo are possible. - All machines are available with full warranty. Ibjdpfx Agjv Nl Hpeysc

Condition: excellent (used), Double STDN pancake baking carousel system. Superb system designed for reliable high volume production of pancakes and crepes, blinis etc. Extremely hard to find on the used market. diameters can be adjusted from 30mm to 240mm and weights from 8g to 100g. New cost of this system is in excess of 500,000. We also have a continuous waffle manufacturing line for sale. Iedoxlra Rspfx Agysbc

Condition: new, functionality: fully functional, power: 375.1 kW (509.99 HP), axle configuration: 4x4, fuel: diesel, emission class: euro6, Year of construction: 2025, Equipment: additional headlights, airbag, parking heater, trailer coupling, From our range of new vehicles, we offer you: TLF 3000 All-Wheel Drive on a rugged MAN TGM 13.290 4x4 Off-road Chassis This vehicle is ideal for small and medium-sized fire departments in rural areas looking for a compact and robust truck capable of handling a wide variety of tasks while providing a large water supply. Chassis: • MAN TGM 13.290 4x4 EURO 6 with 290 HP (213 kW) and automated transmission • Single tires with matching track for excellent off-road capability Cab: • Standard crew cab (1:5) in RAL 3000 (fire red) • Air conditioning and auxiliary heater • Standard 4 SCBA holders in the crew compartment Bodywork: • High-quality frame construction using stainless and corrosion-free materials • Folding steps for each side equipment compartment • Customizable stainless steel equipment mountings to your specifications • Walkable, non-slip roof Vehicle Pump/Extinguishing Agent Tank: • Maintenance-free combined normal/high pressure pump FPN 2000-10 • PUMP&ROLL capable • Output 2,000 l/min at 10 bar and 400 l/min at 40 bar • Integrated, infinitely adjustable foam proportioning system • 4,000 l water tank with integrated 400 l foam agent tank • Additional heating in the pump compartment Firefighting Equipment: • High-pressure rapid intervention line with 50 m of rigid hose • Foam/water monitor (2,000 l/min) mounted on the roof • Self-protection system with 4 nozzles in front of the wheels Iedoxyunaopfx Agysbc Safety and Lighting: • LED lightbar on the roof / 2 LED front flashers • Pneumatic special signal system (Martin horn) • 100 W public address system with microphone • Reversing camera • Comprehensive LED lighting in crew and all equipment compartments • LED perimeter lighting on the superstructure plus additional work lights • Pneumatic LED light mast with remote control • Optional hygiene board available We would be pleased to provide you with a detailed offer and present the vehicle to you at our location in Berlin. All information provided to the best of our knowledge and belief, no guarantee for completeness or accuracy. This advertisement constitutes information only and does not represent a binding offer. Subject to prior sale!

Condition: used, This listing is for the Restek Single Position Base Plate Gas Filter Kit + SGT Gas Filter Kit The unit is in full working condition and is ready for immediate use The Restek Single Position Base Plate Gas Filter Kit is a modular system designed for gas purification in laboratory applications, particularly in gas chromatography (GC) and mass spectrometry (MS) systems. Key Features Baseplate Design: The single-position baseplate (catalogue number 22025) is constructed from brass and measures 10.2 × 10.2 × 4.8 cm. It is compatible with all standalone Super Clean gas filters Filter Cartridges: Restek offers various filter cartridges, such as the triple filter that removes oxygen, moisture, and hydrocarbon impurities, and the fuel gas filter designed for moisture and hydrocarbon removal. Fitting Compatibility: The baseplate accepts 1/8" tubing. To adapt to 1/4" tubing, 1/8" to 1/4" tube end reducers are available. Material Options: End fittings are available in brass or stainless steel, allowing for customization based on application requirements Ijdsxv Dk Nopfx Agyebc Restek SGT Superclean Gas Filter Kit The Restek SGT Superclean Gas Filter Kit is a high-purity gas purification system designed to remove contaminants such as moisture, oxygen, and hydrocarbons from carrier and fuel gases used in gas chromatography (GC) and mass spectrometry (MS). This kit is particularly beneficial for applications requiring ultra-pure gas supplies to ensure accurate and reliable analytical results. Key Features High-Purity Output: Delivers gas purity levels exceeding 99.9999%, depending on the incoming gas quality and flow rate. Versatile Compatibility: Compatible with various gas types, including inert carrier gases, air, hydrogen, and helium. Quick-Connect Design: Features a user-friendly quick-connect system for easy and leak-free filter cartridge changes. Durable Construction: Constructed with a glass interior to prevent diffusion and a polycarbonate exterior for safety. Visual Indicator: Each filter cartridge includes an easy-to-read color change indicator to signal when replacement is necessary.