Single Eccentric Off-Set Disc Butterfly Valve

SINGLE ECCENTRIC OFF-SET DISC BUTTERFLY VALVE

A New Angle on Pressure

Available as: Wafer Type, Lugged Type and Steam Jacketed

A NEW GENERATION OF PAL BUTTERFLY VALVES

On going research and development of a unique design of butterfly valve capable of handling higher pressures and temperatures and more aggressive process conditions than conventional butterfly valves.
An ideal substitute for ball and plug valves.

MATERIAL SELECTION & CONSTRUCTION
A SIMPLE NUMERIC/ALPHABET SYSTEM TO IDENTIFY MATERIALS OF CONSTRUCTION

Pipe
Size
(mm)

Body
Material

Disc
Material

Shaft
Material

Disc
Seal

Disc &
Shaft
"O" Rings

Operation

LM25 Aluminium

304 ss

PTFE

Nitrile

Lever Operator

LM25 Hard
Anodised

316 ss

Filled
PTFE

Viton

Lever Operator
With Lock Up

100

Carbon Steel (ENC)

Carbon Steel
(ENC)

EN57(17-4PH)

UHMWPE

Silicone

150

CF8M Stainless
Steel

CD4

Peek

F.E.P

Bare Shaft

200
40 Bar

904 L

Metal

EPDM

Gear
Operator

CD4 MCu. Duplex
Stainless Steel

PAL 28

Pneumatic

250
40 Bar

Monel 400

Electric

Alloy 20-CN7M

RuthAlloy

Hydraulic

200

PAL 28

250

CB7-P.H.

Monel - M35

RuthAlloy

EXAMPLE: 100mm alloy 20 valve with 904 L shafts, reinforced PTFE disc seal ring, VITON disc and shaft seals with lever and lock up attachment. By using the legend, the above description is converted to a type:

SIZE	BODY-DISK-SHAFTS	BODY SEAL	"0" RINGS	OPERATION
4	AA9	R	V	LU

MATERIAL CHARACTERISTICS

CF8M:	Commonly used alloy for a wide range of applications covering weak to mild acids, alkalies and where product contamination resistance is essential.
CN7M:	A higher nickel, chrome alloy for improved corrosion resistance for various acid applications showing particularly good results for sulphuric acid across a wide range of temperatures and concentrations.
LM25:	A light weight aliminium alloy with silicone, heat treated for general purpose applications. In the hard anodised form the applications are wider due to the surface structure being converted to a hard formation of aluminium oxide. Vegetable oils, pharmaceuticals, petrol and diesel are some of the many applications.
CD4:	A high chrome super stainless or "Duplex" stainless steel for improved resistance against chloride environment and stress corrosion, often more suitable for higher temperature acids and salts.
PAL28:	An alloy similar to CN7M (Alloy 20) but containing higher nickel, chrome and molybdenum contents for improved corrosion resistance for strong acids deaerated and where chlorides are present.
CB7:	A chrome nickel steel which is percipitation hardened for applications where high abrasion rates are anticipated.
WCB:	A common refinery type cast carbon steel alloy for high temperature conditions. Bodies and discs electroless nickel coated for corrosion resistance. Suitable for non corrosive conditions such as diesel and petrol.

TORQUE FIGURES Nm
Valve size (mm)	Differencial line pressure (kPa)
Valve size (mm)	0	600	1000	1200	1600	2000	2500	4000
50	4	10	11	14	17	21	26	34
80	12	13	25	28	38	50	63	100
100	15	32	38	44	53	63	75	113
150	55	75	113	119	130	175	195	250
200	60	95	125	140	165	225	375	420
250	68	175	255	283	343	402	501	640

Torque Figures Include 25% Safety Factor

FLOW COEFFICIENT CV.
Valve size (mm)	Degrees open
Valve size (mm)	10	20	30	40	50	60	70	80	90
50	0.3	4	11	24	42	64	89	115	143
80	0.3	15	40	67	100	137	190	255	316
100	3	24	66	92	151	220	331	491	645
150	26	81	136	201	314	471	718	976	1247
200	33	177	321	523	802	1197	1737	2607	3827
250	19	168	393	677	1125	1577	2276	3570	5200

As Determined By The Laboratory For Eenergy RAU CV in US GAL/mm.

VALVE SPECIFICATIONS

F-F Dimensions are to BS 5155 (Short Pattern) and API 609 Class A.

Body Flanges Suitable for BS 4504, ASME/ANSI 616.5 Class 150, BS 10 D & E.

Mounting Pads and Offset Square on shafts are to ISO 5211 standards.

Serrated Spiral finish on faces are to ASME/ANSI B16.5.

PAL BUTTERFLY VALVE DESIGN FEATURES

A high strength durable and compact butterfly valve capable of working in high pressure and temperature environments.

Valves are manufactured in a wide range of standard and exotic materials for corrosion resistance against various aggressive chemicals, acids, alkalies and gasses.

The shafts being central to the disc combined with low coefficient of friction seals and bearings, results in the valve having the lowest operational torques compared to other designs of butterfly valves. Substantial savings are thus guaranteed when considering the costs of valve automation.

The self energising disc seal ring as described below combines the unique strength of PTFE, UHMWPE and PEEK with the resilience of elastomeric type '0' rings, resulting in a long life zero leakage simple to replace at low cost valve seal.

A positive disc to drive shaft connection using a slot and tonque system, which eliminates the use of taper pins, keys or fasteners. This also allows for simple and quick disengagement for maintenance purposes.

THE NEW PAL T-TYPE PRESSURE ENERGISED DISC SEAL


Figure 1	Figure 2	Figure 3
The diagram shows the valve in assembled Condition, opened and under no pressure. The lock ring and butterfly disc have shoulders which loosely capture the "T" shaped seal. The seal is positively retained in position by an "0" ring.	The diagram shows the valve in a closed position but under no pressure conditions and contacting the integrally machined seat. The seal ring being dimensionally slightly larger than the seat bore, compresses itself and forces the "0" ring to compress further. The "T" seal moves away from the disc and lock ring shoulders. The "0" ring exerts and upward force that continually energises the disc seal maintaining contact between seal and seat.	The diagram indicates pressure applied from one side of the disc in a closed position. The line pressure automatically exerts an upward force on the underside of the "T" seal, increasing the pressure of the seal at the contact face. The higher the pressure, the tighter the seal. When the disc moves to an open valve position the tension is lost and the components revert to a relaxed position.

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