Drilling mud degassers · Vacuum degasser vessels with dispersion plates and a jet-pump feed (500–1,200 gal/min of water) and atmospheric spray-tank degassers, which strip entrained gas from gas-cut mud downstream of the shakers
A drilling mud degasser removes gas entrained in the mud returning from the well, so that the mud pumped back downhole keeps its weight. Its separation chamber spreads the gas-cut mud thin — over plates under vacuum, or as a spray sheet in an open tank — so bubbles reach the surface and the gas can be vented or flared. Ask three things first: what mud flow rate the degasser must handle, whether a vacuum or atmospheric design fits the rig and pits, and what code, certification and gas routing the location requires.
Mud degassers for oil, gas and geothermal drilling — vacuum degasser vessels with their dispersion plates, floats, jet pumps and vacuum pumps, and atmospheric (spray-tank) degassers. Mud-gas separators (poor boy degassers) on the choke line, shale shakers (see shale shakers), desanders and desilters (see desanders desilters), mud tanks (see mud tanks) and molten-metal degassing (see molten metal degassing system) are outside this page except where compared.
CNFX editorial research · Sources checked October 11, 2026 · 4 sources
NOV describes its Brandt DG degassers as removing gases from gas-cut mud so that the proper mud weight is pumped downhole, aiding blowout prevention, and installed immediately downstream of the shakers and upstream of centrifugal pumps. They are skid-mounted with a Class I Div 1 starter and motor; an external JP-10 jet pump pulls mud into the vessel and spreads it in thin layers over internal fiberglass dispersion plates; a float regulates the liquid level, a fail-safe secondary float keeps mud out of the vacuum pump, and a vacuum pump draws the gas off to be piped away for venting or flaring. [1]
Its DG-ATM atmospheric degassers instead lift mud with a submerged impeller up a riser to spray a baffle plate in a spray tank above the mud surface; the thin, fast sheet hits the tank wall, gas escapes from the top of the tank to atmosphere and the degassed mud flows to the next pit, with no external feed pump. The DG-ATM-6 suits pits 6–8 ft (1.8–2.4 m) deep and the DG-ATM-8 pits 8–10 ft (2.4–3 m) deep. [2]
Give the supplier the rig and mud system layout, maximum mud flow, mud weight and type, expected gas cut, pit depth, available centrifugal feed pump and head, power supply and hazardous-area classification, gas vent or flare routing, vessel code and certification needs (ASME, ABS, DNV, NR-13), and space.
02
Size the feed, vacuum system and vessel
NOV lists the DG-5 at 500 gal/min (1,892 L/min) and the DG-10/12 at 1,000 or 1,200 gal/min (3,785 or 4,542 L/min), rated with water, needing a customer-supplied centrifugal pump of 500 gal/min at 75 ft head, 1,000 gal/min at 75 ft or 1,200 gal/min at 100 ft (23–30 m); each has a 5 hp (3.7 kW) vacuum pump rated at 8–15 in (203–381 mm) of mercury; dimensions run from 54 × 88 × 62 in and 2,390 lb (1,085 kg) to 73 7/16 × 100 1/4 × 73 9/16 in and 4,440 lb (2,014 kg) for the NR-13 version; the eductor allows degassed mud to discharge up to 20 ft (6 m) away; internals are coated with cold-tar epoxy; and the DG-10/12 NR-13 meets ASME pressure vessel requirements with a U stamp, with ABS, DNV or NR-13 certification available. Performance depends on the feed rate to the eductor. [1]
The DG-ATM units measure 69 × 40 in with heights of 96 in (DG-ATM-6) and 122 in (DG-ATM-8), weigh 1,300 and 1,450 lb, and list 10 hp (7.5 kW) motors. [2]
Editorial calculation: 8–15 in Hg is about 27–51 kPa below atmospheric pressure; 1,200 gal/min is about 4.5 m³/min. [1]
03
Meet the offshore drilling-fluid rule
For wells on the US Outer Continental Shelf, 30 CFR 250.456(g), administered by the Bureau of Safety and Environmental Enforcement (BSEE), states that the operator must install an operable drilling fluid-gas separator and degasser before drilling operations begin and must maintain this equipment throughout the drilling of the well. The same section ties the degasser's job to measurable mud checks: before tripping out, the drilling-fluid conditioning step may be omitted only if the driller's report shows, among other conditions, that the weight of returning drilling fluid is within 0.2 pounds per gallon (1.5 pounds per cubic foot) of the fluid entering the hole; and while circulating, the drilling fluid must be tested at least once each tour for density, viscosity, gel strength, hydrogen-ion concentration and filtration, with results recorded in the drilling fluid report. [4]
Editorial calculation: 0.2 lb/gal is about 24 kg/m³ (0.2 × 119.8), so returning mud that is gas-cut by more than that margin compared with the mud going in fails one of the conditions for skipping the conditioning circulation; a degasser sized for the full return flow is what brings returning mud weight back toward the pumped weight. [4][1]
Requirement in 30 CFR 250.456
Value or condition
What it means for the degasser order
Paragraph (g)
Operable drilling fluid-gas separator and degasser installed before drilling and maintained throughout. [4]
Degasser on site and working from spud; plan spares and service.
Paragraph (a)(2)
Returning fluid weight within 0.2 lb/gal (1.5 lb/ft³) of fluid entering the hole. [4]
Capacity for the full return flow at the expected gas cut.
Paragraph (i)
Tests at least once each tour: density, viscosity, gel strength, hydrogen-ion concentration, filtration. [4]
Sampling point downstream of the degasser.
Paragraph (c)
Fill the annulus before hydrostatic pressure drops 75 psi or every five stands, whichever gives the lower decrease. [4]
Context: mud volume and weight are tracked on every trip.
04
Find mud degasser manufacturers
No manufacturer record has been reviewed for this product yet. Send your specification and CNFX will match it against manufacturer records.
Ask any supplier for degasser type, rated flow and the fluid it was rated with, feed pump requirement, vacuum pump power and vacuum range, vessel code stamp and certificates, internal plates and coating, level control and pump protection, motor and starter hazardous-area rating, gas outlet size, dimensions and weight, and installation guidance.
05
Consider a centrifugal-force degasser for high return flows
SLB's product page for the CD-1800 D-GASSER describes a third design beside vacuum and atmospheric units: a self-contained unit that removes entrained gases, including H2S and corrosive oxygen, from drilling fluid in the return flow with a high-speed centrifugal-force system. SLB states that the system is more powerful than conventional vacuum or impact systems, that the unit generates up to 1,800 gpm with the lowest horsepower-to-gpm throughput ratio, and that it does not need disassembly and reassembly during rig moves. [3]
Editorial calculation: 1,800 gal/min is about 1,800 × 3.785 = 6,813 L/min, 1.5 times the 1,200 gal/min of NOV's DG-10/12 vacuum unit. NOV states its flow rates with water, while SLB's page does not name the rating fluid; ask each supplier for the rating fluid, mud weight and motor power before comparing flow figures. [3][1]
06
Trace what each part does
This is a functional reference built from the sources cited; it is not one maker's specification.
Fill the specification fields with values for your order
A degasser quotation needs values for your rig and mud. The table explains each field, gives published values where a reviewed source states them, and says what to obtain from the supplier.
Field
What it means and published values
Ask the supplier for
Design Temperature (°C)
Not stated in the reviewed sources.
Range.
Volume (m³)
Not stated in the reviewed sources. Flow 500–1,200 gal/min with water. [1]
Vessel volume; flow.
Material
Not stated in the reviewed sources. Internals coated with cold-tar epoxy. [1]
Vessel steel.
Wall Thickness (mm)
Not stated in the reviewed sources.
Thickness.
Connection Size
Not stated in the reviewed sources.
Inlet, outlet, gas.
Surface Finish (μm)
Not stated in the reviewed sources.
Coating.
Weight (kg)
e.g. 1,085–2,014 kg vacuum; 590–658 kg atmospheric. [1][2]
Weight.
Leakage Rate (mL/min)
Not stated in the reviewed sources.
Vacuum tightness.
Design Standard
e.g. ASME pressure vessel, U stamp; ABS, DNV, NR-13 options. [1]
Code; certificate.
08
Send the rig, mud and certification data together
Paste it into your enquiry below or into an email to a maker, then replace every bracket.
Explore company information and manufacturing capabilities, then discuss the scope of your project with a relevant supplier.
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Compiled and source-reviewed by the CNFX editorial team.
Published product pages show what a company offers, not tested performance. Confirm the legal seller, factory and scope for your order. How we source and review
· Page last updated 13 October 2026
Buyer questions
Where is a mud degasser installed?
NOV places its DG degassers immediately downstream of the shakers and upstream of any centrifugal pumps. [1]
How does a vacuum degasser separate gas?
A jet pump draws mud over dispersion plates in thin layers under vacuum, and a vacuum pump removes the gas. [1]
Do atmospheric degassers need a feed pump?
NOV's DG-ATM uses its own submerged impeller and needs no external feed pump. [2]
Are there degassers other than vacuum and atmospheric types?
Yes. SLB's CD-1800 D-GASSER uses a centrifugal-force system and is rated up to 1,800 gpm. [3]
Is a mud degasser required offshore in the US?
Yes. 30 CFR 250.456(g) requires an operable drilling fluid-gas separator and degasser to be installed before drilling begins and maintained throughout the drilling of the well. [4]
Sources and what still needs a direct check
Sources checked 2026-10-11. NOV (Brandt) and SLB make drilling solids-control and degassing equipment; the eCFR text of 30 CFR 250.456 (BSEE) sets the US offshore requirement for a degasser and the related mud checks.
