The Polish Kaiman R-7 Two-Hose Regulator By Dr.-Ing. Lothar Seveke In a country like Poland, with its long Baltic coastline, important inland waters with many hydraulic structures, strong port system and shipbuilding and its own navy, diving has always been significant. The clean-up work and the reconstruction after the gigantic destructions by the II. World War II took place as in the GDR at first with remains of the heavy diving from the pre-war and war time. Following the European development, however, there was also a need for equipment technology for swimming diving, first in the professional sector, then quickly also in the military and even in the recreational sector. However, just as in the GDR and the CSR, there was hardly any foreign currency available to buy on the international market, especially since this technology was also subject to the embargo as a result of the Cold War. Picture: First (known to me) compressed air regulator NEPTUN from 1957 In the Feinmechanische Werkstätten Danzig (Zak?ady Mechaniki Precyzyjnej Gda?sk, abbreviated Z.M.PREC. GDANSK or ZMP, t1p.de/atr1 ), therefore, the two-hose regulator NEPTUN was first developed in 1956 (by Jan Hiszpanski and Marian Grimm) as the core of a 2-bottle light diving apparatus. This was a fairly close CG45 replica, i.e., a two-stage regulator with a diaphragm-controlled, unbalanced first stage (upstream) and simple second stage (downstream), still without directional valves in the mouthpiece and with a French INT connection for 150-bar cylinders. Patent infringements did not play a role at that time because of the unplanned export and the Iron Curtain to Western Europe. About 1,500 units of the NEPTUN were produced from 1957 to 1959 [Wac]. Picture: MORS as successor of the NEPTUN from 1960 This regulator was further developed by Jan Hiszpanski in the ZMP. It was given a DIN connection, but otherwise differed little from its predecessor and more than 2,000 units were produced from 1960 to 1968 under the name MORS (Walrus). In 1968, demands for improved breathing behavior led to the development of a completely different regulator, single-stage and with injector, the KAIMAN. The regulator was developed by Leszek Suchy and manufactured from 1969 to 1978. Lech Suchy left Poland in 1972 and now lives in the USA [Joh]. Picture: Two-hose regulator Kaiman,Photo: D. Surani The Kaiman is a single-stage regulator like the Mistral from La Spirotechnique, but differs significantly from it in that it has an adjustable Venturi nozzle and a DIN connection. The valve opens with the pressure (down stream), that of the Mistral against the pressure (up stream). Another difference is the balancing of the single-stage regulator, as introduced by Gagnan in 1965 for USD's Royal Mistral, but in a different way, see below (whether these procedures are called "balancing" or "compensation" is not to be disputed here, see [Sch], [Sev1]). So it is definitely an independent development, which was of course influenced by the technical state of the art, but contained innovative elements, which was also confirmed by the patent granted for it [Such]. The case has no special features, it is relatively shapely. The surface is chrome-plated, and various finishes are known, from high-gloss to matte to satin. The satin finish is said to have been characteristic for military use. The DIN connection is very short, which is favorable for a tight fit on the diver's back. As with many European two-hose regulators, the lower and upper shells are held together by a quick-closing clamping ring, the screw of which could be sealed after servicing. A connection for a high pressure gauge is not provided. On the associated PTG P-22, one could be screwed to the cylinder bridge. Picture: Opened Cayman The duckbill valve is folded over at the exhalation port and tied off with chord, so that the convoluted tube can be removed without always moving the exhalation valve. Inside, it is prevented from turning over by a metal bracket in the top shell, which was also not so common with other regulators. Picture: Regulator body of the Kaiman (Photo Dusan Surani) The most remarkable feature of the Kaiman is the massive regulator body, on which the height of the diaphragm lever can also be adjusted. The first schematic picture illustrates the inner workings of the body. It first shows how the injector nozzle is made adjustable. With the injector tube turned far out, most of the outflowing air escapes through a bypass hole that is not directed at the inhalation nozzle. The injector effect is so small. The further you screw the tube in, the more the bypass is closed, and the injector acts more and more strongly, until finally the main diaphragm is held down and the Automal blows off. The injector action can therefore be adjusted within this range. Picture: Principle of the operation of the Kaiman The pictures show the balancing of the valve piston of the Kaiman, which was relatively unusual for single stage regulators [sev2], [sev3,], but is almost normal for the first and second stages of today's single tube regulators. Figure: Realistic representation of the balanced valve of the Cayman. The valve piston is pressurized on both sides with the outlet pressure of the valve and is thus quasi balanced. Falling inlet pressure due to decreasing cylinder pressure therefore does not affect the outlet pressure (as much). Gagnan has solved this for the up-stream valve of the USD-Royal-Mistral somewhat differently but with a similar effect. Balancing in the single-stage USD-Royal-Mistral from 1965 [sev2]. The valve is of course a bit more complicated and elaborate in construction due to these parts, as the photo of the disassembled inner workings of the Cayman shows. Picture:Parts of the single stage balanced valve of the Kaiman (Photo: Dusan Surani) The high-pressure port of the Kaiman has a very simple design and is correspondingly easy to disassemble. The part numbers are those from the parts list shown below. The design suggests that an INT port was also provided, but I am not aware of such a port. Picture: High pressure connection of the Kaiman Another highlight of the Kaiman is its mouthpiece, which is connected to the regulator via relatively short corrugated hoses with 25-mm nozzles on both sides, as is common internationally Inhalation nozzle on the regulator seen from the front at 10 o'clock (and not at 2 o'clock as on the MEDI hydromat). Picture: Lower photo Dusan Surani This mouthpiece combines the advantages of the already very good Royal Mistral mouthpiece from La Spirotechnique with intelligent considerations for optimal use of the regulator. As with the RM, the center section is made of very durable hard rubber with a recessed radially offset bite piece, resulting in good wearing characteristics (short lever in the mouth, free access to the nose). The directional valves are located very far inside (small dead space). But better than on the RM mouthpiece, the tube sockets are attached with threaded rings, which on the one hand allows easy opening of the tubes for drying, and on the other hand allows quick alignment of the tubes for comfortable wearing. I thus consider this mouthpiece to be one of the best ever developed for two-hose regulators. The P-22 2x8-liter compressed air diving unit was developed to go with the regulator. The 150-bar cylinders do not have their own valves, the connection is made via a bridge with a central DIN outlet that can be shut off, where the regulator is screwed in. A reserve circuit with pull rod is built into one cylinder outlet, and a pressure gauge with hose is connected to the other. The whole package is thus very compact and without "barbs" that could interfere in caves, wrecks or the like. A back shell and the strapping are right on the bottle pack, typical for use without the jackets that are common today. Buoyancy tubes could be attached between the bottles to reduce downforce. The complete unit was shipped and stored in a solid wooden case. How many regulators and PTG were made is not known to me. However, I have not come across such a part in the GDR in the 70's and, according to my information, it could not be bought freely in the PR Poland either, unlike AVM and Ukraina in the Soviet Union. So it must have been very rare in the non-professional field, even rarer than the Hydromat in the GDR. However, as in the CSSR and the GDR, there has been an active home-building scene in Poland, as shown in [wac]. Since the Kaiman is an indestructible regulator with very good breathing characteristics in its class, there is no reason why it should not still be used today, well maintained by experts, for enthusiast twin-tube diving. For example, I spent a Maldives boating vacation with him without any problems. Its restoration and maintenance are well explained in [joh]. All wear parts, diaphragms, 0-rings, exhalation and mouthpiece valves, convoluted hoses,... are replaceable by available parts remanufactured for other regulators. The following exploded view with parts list should serve as a support, in which the 0-ring dimensions are also given. A minor problem can be the gasket in the valve piston if it is worn. You can replace it with a nylon or Teflon ring, which you have to find or make ;-) In order to use the dual hose regulator without conflicts with the respective dive supervisor, one has to combine it with a modern secondary regulator or equip it with other additions that integrate it safely into today's technical environment, see t1p.de/dn06 Image:Exploded view and parts list of the Kaiman R7 (enlarged image at t1p.de/5feq ) Sources: [joh] Johnson, Peter, The KAJMAN DOUBLE HOSE Regulator - Cleaning & Restoration t1p.de/uxua [jor] Jorgensen, Sven Erik, The Olrik Regulator, TauchHistorie 2018/10, p. 53 t1p.de/u5bx [sch] Scheyer, Werner, Breathing regulator - structure and function (PPT), www.vit-2000.de [sev1] Seveke, Lothar, Regulator Chinese, t1p.de/2vsq [sev2] Seveke, Lothar, CG45 and Mistral, part 2, TauchHistorie 2016/05, p. 18 t1p.de/gqth [such] Suchy, Leszek, Zawór redukcyjny sterowany plucami do powictrznych aparatów oddechowych. (Pressure regulating valve for breathing apparatus), Pat. P120914, 3.6.1967 t1p.de/rpxx [wac] Wachowski, Wieslaw, Polish vintage scuba regulators, lecture KTT 2011 Neustadt, archive HTG t1p.com/rjt0 Additional information at t1p.de/h9ue