Taco 4900 Series Pall ring air separators

Air and Dirt Separators

Taco air and dirt separators remove entrained air, microbubbles, dirt and magnetite from closed hydronic heating and chilled water systems, protecting pumps, coils, control valves and boilers. The 4900 Series Pall ring models remove microbubbles down to 18 microns. The air and dirt models also capture dirt down to 5 microns. The hi-velocity versions carry more than twice the flow on the same pipe size, up to 33,457 GPM. The AC in-line and ACT tangential separators are rated to 375°F, and the 5900 FlexBalance hydraulic separator decouples primary and secondary circuits. All are ASME Section VIII Division 1 vessels from 2 to 36 in, available online at 125 or 150 psi. All products are genuine, factory-new equipment in original manufacturer packaging, sold and supported by Watermain Supply, an independent industrial supplier. Send your system flow, pipe size and pressure for a same-day selection: sales@watermainsupply.com or 1-888.510.4036.

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Taco ACT / ACTF Tangential Air Separator - ASME, 125 or 150 psi, 2 to 20 in
Taco ACT tangential air separators

Taco

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Taco ACT / ACTF Tangential Air Separator - ASME, 125 or 150 psi, 2 to 20 in

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Taco AC / ACF In-Line Air Separator - ASME, 125 or 150 psi, 2 to 20 in
Taco AC in-line air separators

Taco

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Taco AC / ACF In-Line Air Separator - ASME, 125 or 150 psi, 2 to 20 in

From $2,377.73
Taco 5900 FlexBalance Hydraulic and Air Separator - ASME, 125 psi, 2 to 12 in
Taco 5900 FlexBalance hydraulic separator

Taco

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Taco 5900 FlexBalance Hydraulic and Air Separator - ASME, 125 psi, 2 to 12 in

From $5,178.93
Taco 4900 Series Hi-Velocity Air Separator - Pall Ring, ASME, 2 to 36 in
Taco 4900 Series air separators

Taco

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Taco 4900 Series Hi-Velocity Air Separator - Pall Ring, ASME, 2 to 36 in

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Taco 4900 Series Hi-Velocity Air and Dirt Separator - Pall Ring, ASME
Taco 4900 Series air and dirt separator with switchable magnet

Taco

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Taco 4900 Series Hi-Velocity Air and Dirt Separator - Pall Ring, ASME

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Taco 4900 Series Dirt Separator - Pall Ring, ASME, 125 psi, 2 to 12 in
Taco 4900 Series separator, front view

Taco

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Taco 4900 Series Dirt Separator - Pall Ring, ASME, 125 psi, 2 to 12 in

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Taco 4900 Series Air Separator - Pall Ring Coalescing, ASME, 2 to 36 in
Taco 4900 Series air separators

Taco

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Taco 4900 Series Air Separator - Pall Ring Coalescing, ASME, 2 to 36 in

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Taco 4900 Series Air and Dirt Separator - Pall Ring, ASME, 2 to 36 in
Taco 4900 Series air and dirt separator with switchable magnet

Taco

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Taco 4900 Series Air and Dirt Separator - Pall Ring, ASME, 2 to 36 in

From $3,482.76

Air and Dirt Separators

Hydronic Air & Dirt Removal · Taco

Air & Dirt Separators
for Hydronic Heating and Chilled Water

ASME air separators, air and dirt separators, dirt separators and hydraulic separators that keep closed loops quiet, clean and efficient. Pall ring coalescing, tangential and in-line designs from 2 to 36 in, rated flows to 33,457 GPM, for boiler plants, chilled water systems, campuses and data center cooling loops.

Taco 4900 Series Pall ring air separators
2 to 36 inPipe sizes
33,457 GPMMax rated flow, hi-velocity
18 micronMicrobubble removal, 4900
5 micronDirt removal, air/dirt models
ASME VIIIDiv. 1 pressure vessels

Air and dirt are the two contaminants every closed hydronic loop fights. Entrained air and microbubbles cause noise, air-bound coils, corrosion and pump cavitation, and every film of air on a heat transfer surface cuts capacity. Dirt, sand and magnetite wear seals, clog control valves and coat heat exchanger tubes. A correctly sized separator removes both continuously, so the boilers, chillers, pumps and terminal units downstream last longer and run at the efficiency they were selected for.

Watermain Supply supplies the complete Taco separator line online with engineering-led selection: 4900 Series Pall ring air, air/dirt and dirt separators in standard and hi-velocity designs, AC/ACF in-line and ACT/ACTF tangential air separators, and the 5900 FlexBalance hydraulic separator. Send us the system flow, pipe size and pressure and we confirm the model before you order: sales@watermainsupply.com or 1-888.510.4036. All products are genuine, factory-new equipment in original manufacturer packaging, sold and supported by Watermain Supply, an independent industrial supplier.

Separator Selection GuideMatch the separator type to your system Sizing by Flow and Pipe SizeWorked example with rated flows HVAC Pump & Circulator CalculatorSize the loop pump that goes with it

Will a Taco Separator Work for Your System?

The four questions mechanical engineers and contractors ask first, answered from Taco’s published data.

Warranty

The 4900 Series is covered for 1 year from start-up or 18 months from shipment, whichever comes first, under Taco’s limited warranty (IOM 402-080). For the AC, ACT and 5900 series we confirm the current Taco terms with your quote.

Built to Last

ASME Section VIII Division 1 carbon steel vessels, registered with the National Board, with 304 stainless steel Pall rings, baffles or strainers inside. Removable cover models let one person lift the Pall ring basket out for inspection.

The Fit Limits

Closed loop hot water, chilled water and water/glycol. 125 or 150 psi listed online, 250 psi by quote. 240°F on the 4900 Series, 270°F on the 5900, 375°F on the AC and ACT. Not for domestic potable water.

Size It Now

Send system flow, pipe size, design pressure and fluid temperature and we return the Taco model the same day.

Email the Duty

Or call 1-888.510.4036

Taco Air and Dirt Separator Families

Three ways to remove air, and the dirt that travels with it. Start with the job, then pick the size by flow.

Taco 4900 Series air and dirt separator with switchable magnet

4900 Series Air & Dirt Separator

Air, microbubbles and dirt in one vessel

2-36 inPipe sizes
14,905 GPMMax rated flow
5 micronDirt removal
125/150 psi@ 240°F

A bed of 304 stainless steel Pall rings coalesces microbubbles down to 18 microns for the factory air vent, while dirt down to 5 microns settles into the lower section and leaves through the factory-installed blowdown valve. An optional switchable magnet (suffix M) captures magnetite.

  • Factory air vent, flush valve and blowdown valve
  • Removable cover models (R) for top access to the basket
  • Rated at 4.9 ft/sec through the pipe connection
  • Hi-velocity version rated at 11 ft/sec, to 33,457 GPM
Best forNew and retrofit boiler and chiller plants where one vessel should handle air and dirt, especially older systems carrying magnetite.
View 4900 Air & Dirt Separator
Taco ACT tangential air separators

ACT / ACTF Tangential Air Separator

Cyclonic separation to 375°F

2-20 inPipe sizes
9,307 GPMMax optimal flow
375°FMax temperature
125/150 psiASME

The water and air mixture enters through a tangential inlet; the cyclone inside the large chamber separates air and un-dissolved sediment, and the air leaves through the top vent to an automatic vent or a plain steel expansion tank. ACTF models add a removable 304 stainless steel strainer.

  • Cyclonic tangential flow, no internal media
  • Removable 304 SS strainer on F models
  • Base ring standard on 8 in and larger
  • Vent to an air vent or to a compression tank
Best forHigher-temperature hot water systems and air control designs with a plain steel compression tank.
View ACT / ACTF
Taco 5900 FlexBalance hydraulic separator

5900 FlexBalance Hydraulic Separator

Primary-secondary decoupling plus air removal

2-12 inSizes
1,409 GPMMax optimum flow
99.6%Dissolved air, Plus
125 psi@ 270°F

Taco’s patented FlexBalance acts as a hydraulic bridge between the primary and secondary circuits, so the flow in one does not affect the other and the pumps are not coupled. FlexBalance Plus adds Pall ring technology that removes up to 99.6% of dissolved air, so a separate air separator is not needed.

  • Prevents ghost flows and pumps operating in series
  • Brass conical air venting chamber keeps the vent clean
  • Less floor space and pressure drop than field-built components
  • US Patent 7,117,888
Best forVariable primary or primary-secondary boiler plants and multi-boiler or multi-chiller systems with independent loop pumps.
View 5900 FlexBalance

More Taco Separators

Taco 4900 Series stainless steel Pall ring basket

4900 Air Separator

2-36 in · 51 to 14,905 GPM · 18 micron microbubblesStandard or removable coverTaco 4900 Series hi-velocity air separator

4900 Hi-Velocity Air Separator

11 ft/sec rating · 115 to 33,457 GPMSmaller vessel, same pipeTaco 4900 Series hi-velocity air and dirt separator

4900 Hi-Velocity Air & Dirt

11 ft/sec · air plus 5 micron dirt · magnet optionHigh-flow plantsTaco 4900 Series dirt separator

4900 Dirt Separator

2-12 in · 51 to 1,837 GPM · 5 micronDirt only, magnet optionTaco AC in-line air separators

AC / ACF In-Line Air Separator

2-20 in · to 9,307 GPM · 375°F · baffle designThreaded, flanged or grooved

Taco Separator Comparison

The families side by side, from the data on each listing. Highlighted cells are the figures that usually decide the choice.

Series Removes Sizes Flow range Pressure / temp online Method
4900 Air Free air, microbubbles to 18 micron, dissolved air 2-36 in 51-14,905 GPM 125/150 psi @ 240°F Pall ring coalescing, 4.9 ft/sec
4900 Air & Dirt Air plus dirt to 5 micron 2-36 in 51-14,905 GPM 125/150 psi @ 240°F Pall ring, blowdown valve
4900 Hi-Velocity Air Air and microbubbles 2-36 in 115-33,457 GPM 125/150 psi @ 240°F Pall ring, 11 ft/sec
4900 Hi-Velocity Air & Dirt Air plus dirt to 5 micron 2-36 in 115-33,457 GPM 125/150 psi @ 240°F Pall ring, 11 ft/sec
4900 Dirt Dirt to 5 micron, magnetite with magnet option 2-12 in 51-1,837 GPM 125 psi @ 240°F Pall ring, blowdown valve
ACT / ACTF Free air, un-dissolved sediment 2-20 in 104-9,307 GPM 125/150 psi @ 375°F Tangential cyclone, optional strainer
AC / ACF Free air; debris 3/16 in and larger with strainer 2-20 in to 9,307 GPM 125/150 psi @ 375°F In-line baffle, optional strainer
5900 FlexBalance Hydraulic separation; Plus adds air and dirt 2-12 in 63-1,409 GPM 125 psi @ 270°F Baffles or Pall rings

From the Taco submittal data sheets and catalogs on each product page. 250 psi 4900, AC and ACT builds, 300 psi AC builds and 150 psi FlexBalance builds (-61, -62) are quoted on request.

Quick rule. Fluid above 240°F: AC or ACT. Old system with dirt or magnetite: 4900 air and dirt with the magnet option. Tight room or high flow: hi-velocity 4900. Primary and secondary pumps on one plant: 5900 FlexBalance Plus, which replaces the separate air separator too.

Pall Ring, Tangential or In-Line Baffle?

Taco is the separator line we carry today, so the honest comparison is between technologies. Each one wins somewhere.

Question Pall ring coalescing (4900) Tangential cyclone (ACT) In-line baffle (AC) Hydraulic separator (5900)
Microbubbles and dissolved air Down to 18 micron, plus dissolved air Free air Free air Plus models: up to 99.6% of dissolved air
Dirt removal 5 micron on air/dirt and dirt models Un-dissolved sediment; strainer on F Strainer on F, 3/16 in and larger Plus models remove dirt
Max temperature 240°F 375°F 375°F 270°F
Largest size 36 in 20 in 20 in 12 in
Decouples pump circuits No No No Yes
Air control with a compression tank Air vent Vent to air vent or plain steel tank Vent to air vent or plain steel tank Air venting chamber

Verdict. Pall ring coalescing removes the most air and dirt and reaches the largest sizes, so it is the default for modern boiler, chiller and data center loops at or below 240°F. Tangential and in-line separators win on temperature, to 375°F, and fit traditional air control systems that pipe the vent to a plain steel expansion tank. The FlexBalance wins wherever primary and secondary pumps share a plant, because it decouples them and, in the Plus version, removes air and dirt at the same time.

Which Separator Do You Need?

Typical selections by system. Confirm the final size on rated flow and pressure; we check every selection before it ships.

Application Main concern Recommended Notes
Condensing boiler plant, new building Microbubbles, low pressure drop 4900 Air Separator Install on the boiler supply, ahead of the pump suction.
Retrofit of an older steel-piped system Dirt, sludge and magnetite 4900 Air & Dirt with magnet (M) Purge through the blowdown valve on a regular schedule.
Chilled water plant or data center cooling loop High flow, air-free coils 4900 Hi-Velocity Air & Dirt Locate before the chiller, where air is least soluble.
Primary-secondary or multi-boiler plant Pump decoupling plus air removal 5900 FlexBalance Plus Keep the primary-secondary connection short.
High-temperature hot water, above 240°F Temperature rating ACT / ACTF or AC / ACF Rated to 375°F; choose F models for a strainer.
Air control system with a plain steel tank Vent to the compression tank ACT or AC Pipe the top vent to the tank fitting.
Separate dirt removal on an existing air separator Dirt only 4900 Dirt Separator 2 to 12 in, 125 psi online.
Tight mechanical room, large pipe Footprint 4900 Hi-Velocity Air More than twice the flow of a standard 4900 on the same pipe.

Sizing an Air or Dirt Separator

Separators are sized on flow at the pipe connection, then checked for pressure, temperature and fluid. Line size is a starting point, not the answer.

1. Find the system flow

Use the design flow of the loop the separator serves. For water, flow in GPM = load in BTU/hr ÷ (500 × temperature difference in °F). A 2,000,000 BTU/hr boiler loop at a 20°F difference carries 2,000,000 ÷ (500 × 20) = 200 GPM. Glycol mixtures need the manufacturer’s correction for specific heat.

2. Pick the model whose rated flow covers it

Taco rates the standard 4900 Series at 4.9 ft/sec through the pipe connection and the hi-velocity models at 11 ft/sec. The AC and ACT carry an optimal flow per size. Every model’s rating is in the table on its product page.

Worked example: 400 GPM chilled water loop on 6 in pipe. A standard 4900 at 4 in is rated 204 GPM, too small. The standard 6 in model (4906A) is rated 469 GPM and covers 400 GPM on line size. If the room is tight, the hi-velocity 4 in model (4904AH) is rated 458 GPM, so a smaller vessel with 6 x 4 in reducers carries the same duty. With an older system or visible sludge, step to the air and dirt version at the same size (4906AD or 4904ADH) and add the magnet option for magnetite.

3. Check the limits

Design pressure: 125 or 150 psi online, 250 psi by quote. Temperature: 240°F for the 4900, 270°F for the 5900, 375°F for the AC and ACT. Fluid: closed loop water or water/glycol only. Plan the rigging: the large vessels ship by freight and use their lifting lugs for lifting only, never for anchoring or hanging.

Send Us the DutyHVAC Pump Calculator

Rated Flow by Pipe Size

Taco’s rated flow for the Pall ring air and air/dirt separators, standard (4.9 ft/sec) and hi-velocity (11 ft/sec), from the 4900 Series submittals. Read across at your pipe size.

Pipe size 2 in 2-1/2 in 3 in 4 in 5 in 6 in 8 in
Standard 4900 (GPM) 51 73 113 204 306 469 816
Hi-velocity 4900 (GPM) 115 165 253 458 686 1,015 1,730
Pipe size 10 in 12 in 14 in 16 in 18-36 in
Standard 4900 (GPM) 1,291 1,837 2,106 2,790 3,673 to 14,905
Hi-velocity 4900 (GPM) 2,718 4,124 4,727 6,262 8,246 to 33,457

Source: Taco 4900 Series submittal data, as listed on our 4900 product pages. Taco states a pressure drop of 2 psi or less at the optimal flow rate for the standard models. AC and ACT optimal flows run from 104 GPM at 2 in to 9,307 GPM at 20 in; see each product page.

Taco in-line air separator pressure drop chart with strainer

Taco pressure drop chart for the AC in-line air separators with strainer. Charts for every series are in the Data Sheet tab of each product page.

Why Air and Dirt Separation Pays

What a separator does for the equipment around it, and the Taco design details behind it.

Quieter Systems

Free air is the usual cause of gurgling pipes and terminal noise. Removing it continuously keeps occupied spaces quiet after fill and after every service drain-down.

Full Coil Capacity

Air pockets bind coils and baseboard, and microbubbles insulate heat transfer surfaces. An air-free loop delivers the capacity the coils and heat exchangers were selected for.

Longer Pump Life

Entrained air promotes cavitation at the impeller and dirt wears mechanical seals. Separators protect circulators, inline and end suction pumps alike.

Less Corrosion

Oxygen in entrained air drives corrosion of steel and iron. Removing air and dissolved air slows the formation of rust and magnetite in the first place.

Clean Control Valves

Dirt down to 5 microns is captured before it reaches pressure independent and balancing valves, which keeps their small ports working.

Magnetite Capture

The optional high power switchable magnet on 4900 air/dirt and dirt models pulls magnetite out of the flow, and the magnet switches on and off.

Service Without Cutting Pipe

Removable cover (R) models let the stainless Pall ring basket come out from the top, and one person can remove the basket for inspection.

ASME and National Board

Every vessel is designed and built to ASME Section VIII Division 1 and registered with the National Board, the documentation inspectors and owners expect.

Complete the Hydronic System

Equipment that installs alongside a separator in the same mechanical room.

Taco 4900 Series air and dirt separator, front view

Expansion and Buffer Tanks

Taco CA, CBX, CX and PS expansion tanks, BTH/BTL and horizontal buffer tanks and the MPT multi-purpose tank.

Taco U-tube shell and tube heat exchanger

Heat Exchangers

U-tube and Leak Guard shell and tube, TB brazed plate and tank heating units.

Taco 5900 FlexBalance separators

Circulator Pumps

Loop and recirculation circulators to pair with the separator.

Taco 4900 Series air and dirt separator for chilled water

Data Center Pumps and Systems

Pumps, boosters and tanks for data center facility and chilled water systems.

Every Taco separator on this page is genuine Taco equipment, factory-new in original packaging, with its Taco submittal and installation manual on the product page.

Why Buy Separators from Watermain Supply

Engineering-Led Selection

We check flow, pipe size, pressure and temperature against Taco’s published ratings before the order ships. Factory submittal on request.

The Whole Mechanical Room

Separators, expansion and buffer tanks, heat exchangers and pumps on one order, from one supplier, matched to each other.

Multi-Brand Honesty

We sell several pump and tank lines. If a different separator type or size is the better fit for your system, we will say so.

Account Terms Available

Net-30 for qualified mechanical contractor, facility and municipal accounts. PO and credit applications handled in-house.

Freight Handled for You

Large vessels ship by LTL freight. We arrange the shipment and confirm the weight, so you can plan the lift at delivery.

Houston and the Gulf Coast

Based in Houston, Texas, serving engineers and contractors across the Gulf Coast and nationwide.

Frequently Asked Questions

Common questions from engineers, contractors and facility managers selecting an air or dirt separator.

What does an air separator do in a hydronic system?

An air separator removes free air and microbubbles from the water in a closed heating or chilled water loop. Air that stays in the loop causes noise, corrosion, air-bound coils and pump cavitation, and it cuts heat transfer. Taco separators collect the air in the vessel and release it through a top vent, either to an automatic air vent or to a plain steel expansion tank.

What is the difference between an air separator and an air and dirt separator?

An air separator removes air only. An air and dirt separator, such as the Taco 4900 Series air/dirt models, also captures dirt down to 5 microns in its lower section and purges it through a factory-installed blowdown valve. A dirt separator removes dirt only, and is used where air is already handled elsewhere.

How do Pall ring coalescing separators work?

Water passes through a bed of 304 stainless steel Pall rings that deflect the flow in many directions. Microbubbles collide with the ring surfaces, join into larger bubbles and rise to the factory air vent. Taco states the 4900 Series removes microbubbles as small as 18 microns and air that has dissolved in the system water.

Should I choose a standard or a hi-velocity 4900 separator?

Standard 4900 models are rated at 4.9 ft/sec through the pipe connection. Hi-velocity models are rated at 11 ft/sec, so one vessel handles more than twice the flow on the same pipe size. Choose hi-velocity where the mechanical room is tight or the flow is high; choose standard where you want the lowest pressure drop for the size.

When do I need a tangential (ACT) or in-line (AC) air separator instead of a Pall ring model?

The AC in-line and ACT tangential separators are rated to 375°F, against 240°F for the 4900 Series, so they suit higher-temperature hot water systems. They remove free air with a baffle or a cyclone, and the F models add a removable 304 stainless steel strainer. The 4900 Series goes further on microbubbles and dissolved air.

What is a hydraulic separator and when is it used?

A hydraulic separator is a low pressure drop bridge between the primary and secondary circuits of a hydronic system, so the flow in one circuit does not affect the other and the pumps are not hydraulically coupled. The Taco 5900 FlexBalance does this job, and the FlexBalance Plus adds Pall ring air and dirt removal so a separate air separator is not needed.

Where should an air separator be installed?

Install it where air is least soluble: on the supply side after the boiler or heat exchanger, or before the chiller, and ahead of the pump suction. Connect the expansion tank on the suction side of the pump. Separators are designed to be self-supporting in the piping; Taco must review any external piping loads.

How do I size an air separator?

Pick the model whose rated or optimal flow covers your system flow at the pipe size, and check the pressure rating and temperature. Each listing on this page gives the rated flow for every model. Send us the system flow, pipe size, pressure and temperature and we will confirm the Taco selection.

What warranty comes with Taco 4900 Series separators?

The 4900 Series is covered for 1 year from start-up or 18 months from shipment, whichever comes first, under Taco’s limited warranty (4900 Series IOM 402-080). For the AC, ACT and 5900 series, ask us and we will confirm the current Taco terms before you order.

Can these separators be used on domestic potable water?

No. These separators are carbon steel vessels for closed loop hot water, chilled water and water/glycol systems. Potable water corrodes carbon steel, so they are not for domestic water service.

Ready to Select Your Separator?

Send the system flow, pipe size, design pressure and fluid temperature. We reply the same day with the Taco model, lead time and freight.

1-888.510.4036 Selection Guide Email sales@watermainsupply.com Request a Quote
Technical data on this page is taken from Taco product literature and is subject to change by the manufacturer. Confirm against the current installation manual before specifying.
Taco and FlexBalance are trademarks of Taco, Inc., used here for product identification only.
Watermain Supply is a DBA of E4 Industrial LLC, an independent industrial supplier based in Houston, Texas.