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Series F7-MS Multi-Station Level Switch

Series 291/293/294 Welded Chamber Level Control

Series 251/253/254 Welded Chamber Level Control

External Mount Pressure to 1250 psig, Hermetically Sealed Switches, Temperature to 750°F, Explosion-Proof Housings

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Series 251/253/254 Welded Chamber Level Control, time proven magnetic head leak proof construction combines with a heavy duty welded chamber to provide excellent reliability for control of compatible liquids. Operating pressures of 1250 psig (86 bar) at 650°F (345°C) and 750 psig (52 bar) at 750°F (400°C) are standard. The use of an external magnet reduces the possibility of magnetic particle build up inside the armature tube and subsequent loss of operation as may occur with the internal magnet repulsion design. The controls feature carbon steel bodies and stainless steel internal trim. Process mounting configurations include either side/bottom combination 1" NPT/socket weld hubs, side/bottom flanges or side/side flanges. A variety of hermetically sealed snap action or mercury switches are available in SPST, SPDT, or DPDT action for single or two stage operation. Mercury or Gold alloy snap action contacts are suitable for low current DC applications. A full range of switch enclosures are offered. Many chamber, enclosure and switch combinations are UL approved.

Ordering

Grouped product items
Model	Description	Availability*	Qty	Price

Specifications

C1-75:: Minimum specific gravity 0.75. Process pressure 1250 psig (86 bar) at 100°F (38°C), to 650°F (345°C). 750 psig (52 bar) at 750°F (400°C).*
*Heat fins and/or high temperature switches should be considered for process temperatures above 500°F (260°C).
Temperature Limit:: Ambient Temperature: 212°F (100°C); Process Temperature: 750°F (400°C).*
*Heat fins and/or high temperature switches must be used for process temperatures above 500°F (260°C).
Switch Types:: Snap action or mercury.
Electrical Rating:: See Model Chart.
Wiring Connections:: G, WT or E enclosure, terminal block. EV enclosure 189 (460 mm) leads.
Process Connections:: Combination 1" NPT/socket weld hubs or flanges. See model chart.
Wetted Parts:: C1 construction, carbon steel, 303SS, 304SS, 316SS, 430SS. (Optional 316SS with 430SS).
Enclosures:: G painted steel and aluminum. WT, painted steel, aluminum and neoprene. E, aluminum. EV, aluminum, neoprene.
Weight:: 251: 40 lb (18 kg); 253: 50 lb (22.7 kg); 254: 57 lb (25.8 kg).
: Suggested Specifications:
Liquid level control shall be 251 (253) (254) Series with combination 1" NPT/socket weld hubs (flanged) process connections. Chamber shall be welded carbon steel (316SS) suitable for operation at 1250 psig (86 bar) at 100°F (38°C) to 650°F (345°C), 750 psig (52 bar) at 750°F (400°C) at a minimum specific gravity of 0.75. Circuit shall be (hermetically sealed) snap action (mercury) switch (SPST) (SPDT) (DPDT). Enclosure shall be general purpose (weather proof) (explosion-proof) (explosion-proof – vapor proof). Switch mechanism shall be gravity return and shall be activated by a stainless steel float.

Support Library

Approvals

Drawings

Model Chart

EXAMPLE	251	WT	7810	C1	60		251-WT-7810-C1-60 Liquid Level Control, welded carbon steel chamber, weatherproof enclosure, SPDT snap switch, fixed deadband, automatic reset, operating pressure 350 psig (24 bar) at 100°F (38°C), 300 psig (21 bar) at 600°F (315400°C), side/bottom 1" NPT, minimum specific gravity 0.60.
CONNECTION	251						One Vertical and One Horizontal 1" NPT
	253						One Vertical and One Horizontal Flanged Connection
	254						Two Vertical Flanged Connections
ENCLOSURE		G					General Purpose, NEMA 1
		WT					Weatherproof, NEMA 3R, 4, 4X
		E					Explosion-proof, NEMA 7, 9, Class I Groups B, C, D, Class II Groups E, F, G
		EV					Explosion-proof/Vapor-proof, NEMA 7, 9, Class I Groups B, C, D, Class II Groups E, F, G
CIRCUITS (for electrical circuits see charts A & B below)			48XX				Single Stage Mercury Switch, see chart A
			48XX-XX				Two Stage, Mercury Switch, see chart A
			78XX				Single Stage, Snap Switch, see chart B
			78XX-XX				Two Stage, Snap Switch, see chart B
			98XX				Single Stage, High Capacity DC Snap Switch, use heat fins (HF) if process temperature exceeds 350°F (177°C), do not exceed 450°F (232°C), see chart B
			98XX-XX				Two Stage, High Capacity DC Snap Switch, use heat fins (HF) if process temperature exceeds 350°F (177°C), do not exceed 450°F (232°C), see chart B
CHAMBER MATERIAL				C1			Carbon Steel Body
				HFC1			Heat Fins, Carbon Steel Body
				C216			316SS Body
				HFC216			Heat Fins, 316SS Body (251 only)
				C217			316SS Housing with Shield (251 only)
MINIMUM SPECIFIC GRAVITY					60		0.60 Specific Gravity (251 only)
					75		0.75 Specific Gravity (251 only)
					160		0.60 Specific Gravity & 150# Flange (253, 254 only)
					175		0.75 Specific Gravity & 150# Flange (253, 254 only)
					360		0.60 Specific Gravity & 300# Flange (253, 254 only)
					375		0.75 Specific Gravity & 300# Flange (253, 254 only)
					660		0.60 Specific Gravity & 600# Flange (253, 254 only)
					675		0.75 Specific Gravity & 600# Flange (253, 254 only)
OPTIONS						STW	SS Tag Wired
						01	Breather Only (E-Housing only)
						02	Drain Only (E-Housing only)
						12	Breather & Drain (E-Housing only)
						23720	Fungus Proofing

CHARTS A & B - ELECTRICAL CIRCUITS AND RATINGS

SWITCH TYPE	SWITCH ACTION	ELECTRICAL RATINGS IN AMPS						ORDERING CODE
		AC			DC			SINGLE STAGE	TWO STAGE
		120V	240V	440V	30V	125V	250V	SINGLE STAGE	LOWER	UPPER
CHART A Mercury Contacts	SP-ST open on level FALL	10	5	3†		10	5	-4821	-4821	-21
	SP-ST open on level RISE	10	5	3†		10	5	-4820	-4820	-20
	SP-DT one switch	4	2	1†		4	2	-4810	-4810	-10
	SP-DT two switches E.I.*	10	5	3†		10	5	-4815	-4815	-15
	DP-ST two switches E.I.* open on level FALL	10	5	3†		10	5	-4813	-4813	-13
	DP-ST two switches E.I.* open on level RISE	10	5	3†		10	5	-4814	-4814	-14
	DP-DT two SP-DT switches	4	2	1†		4	2	-4806	-4806	-06
CHART B snap action contacts	SP-DT one switch	12	5	3†		0.5**	0.25**	-7810	-7810	-10
	DP-DT two SP-DT switches	12	5	3†		0.5**	0.25**	-7806	-7806	-06
	SP-DT one hermetically sealed switch	5	5		5**			-7810HM	-7810HM	-10HM
	DP-DT two hermetically sealed SP-DT switches	5	5		5**			-7806HM	-7806HM	-06HM
	DP-DT two SP-DT switches	10	3			10‡	3‡	-9806	-9806	-06
	SP-DT one switch	10	3			10‡	3‡	-9810	-9810	-10
	DP-DT Two SP-DT switches	2	2			0.4**	0.25**	-1006	-1006	-06
	SP-DT one switch	2	2			0.4**	0.25**	-1010	-1010	-10

†Available on special order, change 1st digit in ordering code from 4 to 5 or 7 to 8, i.e., -4820 becomes -5820, -7810 becomes -8810, etc.
‡10 amp inductive (polarized) at 125 VDC.
*Electrically Independent.
**Resistive.

FAQ

Questions

Question

Why is the minimum specific gravity important on the float level switches?

Answer

If a medium has a lower s.g. than the rated minimum for a float, the float will sink through the media and the switch will not operate.

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