Technical Datasheet Performance Vapour Pressure and Gas Filled Temperature Switches 700 Series • Precision stainless steel mechanism for arduous atmospheres and high humidity. • Set point adjustable over whole range against calibrated scale with tamperproof adjuster. • Weatherproof and Flameproof models. • Models for fixed switching differential, adjustable differential and HI-LO operation. • Hermetically sealed microswitch option. • ATEX and IECEx Product applications Performance characteristics The 721 is suitable for a wide range of applications in many Industry sectors: • Oil & Gas • Chemical • Petrochemical • Refining System options • Stainless Steel capillary system and Brass Bellows (standard) • Stainless Steel capillary system and Bellows • Power • Food Industry The choice of models available ensures • Rigid stem. that the 721 is suitable for use in: • Corrosive atmospheres Standard Electrical ratings • Resistant to chemical attack • Refer to table 6 Process connection • 3/8 NPT External Sliding Gland, ½ NPT External Direct mounting. How can we help you? Delta Controls’ range of reliable Unit weight Accuracy • Set point repeatability ± 0.5% of span at 20 °C / 68 °F ambient. • Scale accuracy ± 2% of full scale. customised to meet individual requirements. For technical advice or to discuss your application please contact us on +44 (

Enclosure FINISH All enclosures except Type A are finished in light grey epoxy resin paint. Special finishes to order. INTRINSIC SAFETY Because of the low voltages and currents of I.S. circuits, we recommend using gold and/or sealed contacts. WEATHERPROOF ENCLOSURES General Purpose The basic enclosure is pressure die-cast in zinc alloy, offering weather protection not less than NEMA 4 + 13/IP66. For Aggressive Atmospheres Investment cast enclosure in austenitic stainless steel with weather protection not less than NEMA 4X + 13/IP66. FLAMEPROOF ENCLOSURES CATEGORY 2 (ZONE 1) NOTE: Enclosure K...

Electrical Entry Adaptors are available for other popular thread sizes. Enclosures ‘W’ and ‘N’ Standard option code 1(22mm dia) is provided with a nylon 22/20 reducer and fibre washer suitable for a standard M20 cable gland and back nut. Option code 0 elbow adapter is factory fitted. Adapter kits may also be provided retrospectively to fit at site if required. Ask for details. See diagram in DIMENSIONS ‘W’ and ‘N’ SAFETY NOTE If a metal cable gland is site fitted it must either be earthed locally or an earth/gland plate must be used to connect the body of the gland at the enclosure earthing point....

Setting Ranges Table 5A – Deg C Tmax = maximum working temperature NOTE: All models have a bulb diameter of 12mm (0.47in). Models 721-3, 731-4 and 781 have a bulb length of 80mm (3.2in). Models 771-4 have a bulb length of 140mm (5.5in).

Switching Options A much wider variety of switching options can be engineered to customer’s requirements for Model 721, 731, 771 temperature switches, manual latching, pneumatic output etc. Please consult our engineers for further information. Model 721, 731, 771 IEC 947-5-1/EN 60947-5-1 Rating Designation & Utilization Category UL/CSA Rating (RESISTIVE) §SEE NOTE 5 Amps @ 110/250V AC Light Duty for AC only Rated operational current Ie (A) at rated operational voltage Ue VA Rating Make Break Ui 5 Amps @ 110/250V AC & AC14 D300 0.6/0.3A @ 120/240V AC 2 Amps @ 30V DC 250V 0.8kV DC13 R300 0.22/0.1A...

Process Connection Adaptors to other threads are available as optional extras. Other thread specifications and sizes are available without using adaptors. See DIMENSIONS Options & Treatments Code 3/8 –18 NPT EXT Sliding Gland (System Code A to H Table 4) 1/2 – 14NPT EXT Sliding Gland (System Code S, T Table 4) Combinations available, apply for details. Code Tropicalisation High humidity environment Marine and Offshore Saline atmosphere or salt spray Ammonia Process (wetted) parts and construction suitable for atmospheric ammonia. Oxygen Service 2: Process (wetted) parts are cleaned for oxygen....

Performance Data Celsius Units (ºC) TABLE 10A FIXED SWITCHING DIFFERENTIAL Models 734, 774, 781 the switching differential on each point may be up to 1.5 times that of Table 10A & 10C. Care must be exercised, therefore, in specifying high differential switches or set point separation less than 3 times switching differential. TABLE 10B ADJUSTABLE SWITCHING DIFFERENTIAL TABLE 10C FIXED SWITCHING DIFFERENTIAL TABLE 10D ADJUSTABLE SWITCHING DIFFERENTIAL Due to manufacturing tolerances, the figures quoted in these tables are for guidance only. Should the differential be critical for specific applications,...

Technical Specifications ACCURACY Set point repeatability + 0.5% of full scale at 20°C ambient. Scale accuracy +2% of full scale. MAXIMUM WORKING PRESSURE ELECTRICAL CONNECTIONS Terminal Block Cable entry is to a non-pinching block made of a non-hygroscopic thermosetting plastic, suitable for cables up to 2.5mm2/14AWG. NOTE: For models 721-3, 781 scale accuracy will be affected by relative position of head and sensing bulb i.e., sensing bulb 1 metre above/below head Earthing/Grounding An earthing stud is provided inside all = set point shift minus/plus 1% of full weatherproof enclosures, adjacent...

CENELEC / ATEX II 2 G D (Enclosure Codes H and K and all models). Certified to CENELEC EN50 014, EExd IIC T6 (-60 to+40°C), EExd IIC T4 (-60 to +80°C) EN50 018, EN50 021-1-1 (DUST), EN5028-1-1 (DUST) For use in Zone 1 hazardous areas. Category 2. Certificate number BASOIATEX2426X IECEX APPROVAL for use in Zone 1 hazardous areas Exd IIC certified to IEC 60079-0 and IEC60079-1 Cert No. IECExITS04 0006X Rigid Stem – Model 731-4 SLIDING GLAND THREAD Capillary Version – Model 721-3, 771-4, 781 PROPRIETARY GLAND SLIDING GLAND THREAD